In this workshop, we will talk about choosing the best codec for your needs be it for encoding your files or making your own recordings. Although here we are only looking at four major codecs which are MP3, AAC, WMA and Ogg Vorbis (not necessarily in that order). For our experiments, we will take a source file that is an uncompressed PCM .wav file approximately worth 43MB of disk space. Using software that is freely available on the Internet, for instance the LAME MP3 encoder we will encode this file to a smaller size both using lossy and lossless formats and compare these results. So let’s get on with it.
Windows Media Player 10
We have chosen this particular version of Windows Media Player since it lets you encode files in the MP3 format too, other than Windows Media Audio.
Windows Media Player does not let you encode .wav files off your hard drive. What you can do is rip music of a CD. Nevertheless, here is how you can compare your results. First off, rip the song that you want to encode to a .WAV file using a free software such as EAC or dBPowerAmp to your hard drive. Next use Windows Media Player to rip the same song from the CD to a .WMA file and compare the results. The steps below will make this more clearer for you.
In Windows Media Player 10, click on the Rip tab in the default Window or from the Menu Bar, click on View-Go To- Rip. This will take you to the CD track list window.
Now click on Tools-Options. This will open a new window. Click on the Rip Music tab in this Window. In the Rip Settings box, under the Format drop down list you will see the options available for ripping the track from the CD.
Choose any of the option that you want. If you are of the audiophile kind, the best would obviously mean choosing the Windows Media Lossless. As part of the Microsoft DRM program, this option lets you choose if you want to copy protect the music. You can check this box if you want. Now, that we are done with the settings lets start with the ripping. For this, just press the Rip Music in the Windows Media Player window.
Lets compare the sizes now. After ripping the song using the lossless codec, the file size 30.1MB is about 11MB lesser than the original .WAV file. What about the sound quality? Much, much better than the regular 128Kbps MP3 file. The average bit rate for this file is 1041Kbps which is much higher than the even the highest MP3 encoding rate which is 320Kbps.
In a similar manner, you can choose MP3 to be the file type of the music that you are ripping in the Rip Music options and rip the song. Our 43MB file in this case is compressed to approximately 10MB file at a bit rate of 320Kbps. Sound quality is good but if you listen really closely, there will be points where you can make out the difference between the original and the compressed files.
AAC
AAC or Advanced Audio Coding is a MPEG-2/MPEG-4 and is the audio codec of choice for Internet, wireless and digital broadcast. This is a good option if you want to stream audio or want your audio to consume a smaller footprint of your total data. AAC encoding is extremely efficient and easily surpasses the MP3 codec and provides surround sound options. The MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony and Nokia developed AAC, top of the line companies, also involved in manufacturing equipment that affects our daily lives.
For converting our .WAV audio file to an AAC file, we will need to use iTunes which is freely downloadable from the Apple website. Once you have downloaded and installed the software, follow these instructions to create your AAC file.
First click on File -> Add File to Library, then browse, and locate the file that you want to encode.
After adding the file, we will need to set the settings for encoding this file. For this go to Edit-Preferences and in the new window that opens click on the Importing Tab. Here you will see that, similar to Windows Media Player, above there are a lot of codec options including Apple Lossless for you to encode your .WAV file with. You will also see a WAV file encoder that will let you encode your Audio CD tracks to WAV files using iTunes. Next, we choose the AAC Encoder option. By default the option is set to 128 Kbps which we will not choose. Click on the drop down list and choose Custom which will pop up a new window asking you to configure the various settings as you like.
Once you are done making the changes, click on OK twice. Now right click on the file that you want to encode to AAC and then click on the Encode to AAC option. This will start the process. After encoding the file at 320Kbps, the file size is similar to the MP3 file that we made earlier. The sound quality, though, is better than the MP3 file.
Ogg Vorbis
Ogg Vorbis is an open-source audio codec that is still being developed as an answer to both MP3 and AAC. It supports multi-channels and also high bit-rate encoding that rivals the sound quality of any MP3 or for that matter any AAC file. For our workshop, we will use a tiny utility called the oggdropXPdV.
This is a tiny (literally) GUI utility that lets you encode your WAV files to Ogg Vorbis format files.
For this simply drag your .WAV files in the fish box as seen in the screenshot to start encoding.
But before we start encoding we will need to set the encoding quality options, that will let us compare it with our previous files. For doing this, simply right click on the Fish icon box and then click on Encoding options. The above image is what you will see. Here click on the radio button under Bitrate Management and choose CBR mode and choose the nominal bitrate as 320Kbps. You can also go higher, but lets keep it at this to be able to compare the resultant file with the previous files. Now, drag your .WAV file in to the Fish icon box and the encoding process starts. Even this file is the same file size at 320Kbps. The sound quality is better than MP3 and easily comparable to the AAC file.
This workshop was intended to provide you with a glimpse of what you can do and what options are available for you to use when encoding music. Of course, audio is very subjective and you will need to carry out your own experiments to come up with the best solution for your specific needs.
Showing posts with label Digital Audio. Show all posts
Showing posts with label Digital Audio. Show all posts
Sunday, 18 March 2007
Saturday, 17 March 2007
Super Audio Compact Disc (SACD)
The SACD has been developed by the same two companies, which gave us the CD, Sony and Philips. While both these companies are also a part of the DVD Forum, they have gone ahead and brought out a product that directly competes with the DVD-Audio format.
The SACD utilizes a completely different way of encoding music on to a CD. While DVD-Audio discs use PCM (Pulse Code Modulation)/LPCM (Linear PCM) and MLP (Meridian Lossless Packaging) {PPCM- Packed PCM} techniques to contain music on a disc, SACD utilizes a technology called DSD (Direct Stream Digital) and DST (Direct Stream Transfer). Both these technologies are innovative but it is PCM, which represents music more truly than the SACD DSD technology. However, the bandwidth provided by these technologies for playing music is more than enough for pleasing any audiophile.
One of the main drawbacks of the SACD is that the current implementation of the SACD is audio only and does not contain any other information for the tracks that some DVD-Audio discs offer। However, the SACD has an advantage in terms of market acceptance since there is a version of SACD available called the Hybrid Disc.
which has been available for a long time even before DVDPlus discs were introduced. Similar to the DualDisc, the Hybrid disc contains one high-density SACD layer that is only visible to SACD players while the CD layer is visible to the regular CD players. So you get the best of both worlds. So how do these formats compare with each other? Let this table give you a heads-up on that.
With these newer formats, digital audio has been completely transformed. Technologies such as MLP and DSD have packed more information on one single disc without losing information that the quintessential audiophile will miss. Welcome to the new wave of audio!
Companions on the move
The Walkman or for that matter the Discman remains the mode of portable music for people on the move. However, with the advent of digital music and the iPod (of course!) the Digital Audio Player is now on the warpath to become the new portable audio solution for people on the move.
Digital Audio Players or MP3 players as they are known commonly debuted in September 1998 with the release of the Rio 300 portable MP3 player from Diamond Multimedia. Nevertheless, with that came a lawsuit from the RIAA that prevented Diamond from selling its players to prevent piracy. Diamond counter-sued and after a bitter legal battle, Diamond Multimedia finally won the lawsuit. By the summer of 1999, the Rio 300, along with the Creative Nomad and other portable players, became the new, must-have gadgets around the world.
The first players were only able to playback MP3 files and were not free of the occasional hiccups that made the pleasure of listening to music on the go, a sudden death wish. The players would hang playing music or playing back VBR encoded MP3 files that was a more common malady. Nevertheless, as with every new technology, each new generation brings in improvements and newer additions. Today, a MP3 player or Digital Audio Player (to be more politically correct) can playback MP3/WMA/OGG/ASF/AAC and other file formats. Even the most basic Digital Portable Audio Players available today can playback MP3 and WMA encoded files while the other file types are optional.
Talking about Digital Portable Audio Players, how can we miss the Apple iPod? One look at an iPod and anyone will be hooked on to it. The Apple iPod is more than responsible for making Digital Portable Audio Players a rage amongst the masses.
Newer players that do not sport the iPod tag are also available and their features sometimes far surpass those present on the iPod. However, the iPod still remains an icon when it comes to owning a Digital Portable Audio Player.
The SACD utilizes a completely different way of encoding music on to a CD. While DVD-Audio discs use PCM (Pulse Code Modulation)/LPCM (Linear PCM) and MLP (Meridian Lossless Packaging) {PPCM- Packed PCM} techniques to contain music on a disc, SACD utilizes a technology called DSD (Direct Stream Digital) and DST (Direct Stream Transfer). Both these technologies are innovative but it is PCM, which represents music more truly than the SACD DSD technology. However, the bandwidth provided by these technologies for playing music is more than enough for pleasing any audiophile.
One of the main drawbacks of the SACD is that the current implementation of the SACD is audio only and does not contain any other information for the tracks that some DVD-Audio discs offer। However, the SACD has an advantage in terms of market acceptance since there is a version of SACD available called the Hybrid Disc.
| Comparing the newer formats | ||||||||
| | ||||||||
| | | DVD Video | | DVD Audio | | SACD | | DVDPlus\DualDisc |
| High resolution audio | | No | | Yes | | Yes | | Yes |
| | | | | | | | | |
| Multi-channel audio | | Yes | | Yes | | Yes | | Yes |
| | | | | | | | | |
| Audio coding | | DD/DTS/PCM | | PCM/MLP | | DSD & DST | | PCM/MLP |
| Max bit rate | | 6.144 | | 9.6 | | — | | 9.6 |
| (Mb/s) | | | | | | | | |
| | | | | | | | | |
| Video and still images | | Yes | | Yes | | No | | Yes |
| | | | | | | | | |
| Menus & Navigation | | Yes | | Yes | | No | | Yes |
| | | | | | | | | |
| Copy protection | | Weak | | Strong | | Stronger | | Strong |
| | | | | | | | | |
| Plays on DVD-V player | | Yes | | Yes | | No | | Yes |
| | | | | | | | | |
| Plays on DVD-A player | | Yes | | Yes | | No | | Yes |
| | | | | | | | | |
| Plays on CD player | | No | | No | | Yes (Hybrid) | | Yes |
which has been available for a long time even before DVDPlus discs were introduced. Similar to the DualDisc, the Hybrid disc contains one high-density SACD layer that is only visible to SACD players while the CD layer is visible to the regular CD players. So you get the best of both worlds. So how do these formats compare with each other? Let this table give you a heads-up on that.
With these newer formats, digital audio has been completely transformed. Technologies such as MLP and DSD have packed more information on one single disc without losing information that the quintessential audiophile will miss. Welcome to the new wave of audio!
Companions on the move
The Walkman or for that matter the Discman remains the mode of portable music for people on the move. However, with the advent of digital music and the iPod (of course!) the Digital Audio Player is now on the warpath to become the new portable audio solution for people on the move.
Digital Audio Players or MP3 players as they are known commonly debuted in September 1998 with the release of the Rio 300 portable MP3 player from Diamond Multimedia. Nevertheless, with that came a lawsuit from the RIAA that prevented Diamond from selling its players to prevent piracy. Diamond counter-sued and after a bitter legal battle, Diamond Multimedia finally won the lawsuit. By the summer of 1999, the Rio 300, along with the Creative Nomad and other portable players, became the new, must-have gadgets around the world.
The first players were only able to playback MP3 files and were not free of the occasional hiccups that made the pleasure of listening to music on the go, a sudden death wish. The players would hang playing music or playing back VBR encoded MP3 files that was a more common malady. Nevertheless, as with every new technology, each new generation brings in improvements and newer additions. Today, a MP3 player or Digital Audio Player (to be more politically correct) can playback MP3/WMA/OGG/ASF/AAC and other file formats. Even the most basic Digital Portable Audio Players available today can playback MP3 and WMA encoded files while the other file types are optional.
Talking about Digital Portable Audio Players, how can we miss the Apple iPod? One look at an iPod and anyone will be hooked on to it. The Apple iPod is more than responsible for making Digital Portable Audio Players a rage amongst the masses.
Newer players that do not sport the iPod tag are also available and their features sometimes far surpass those present on the iPod. However, the iPod still remains an icon when it comes to owning a Digital Portable Audio Player.
Friday, 16 March 2007
Choosing the right codec
Codecs are abundantly available on the Internet and are included in applications that let you use them to your advantage. In this section, before we get into using these codecs, let’s get one thing clear. If you are making a recording of your own song or audio track, it is best to do it uncompressed in a format such as .wav or .pcm. If you are looking to make archives of your old tapes or vinyl LP’s then you can be sure that using the above mentioned file formats will help you get the best results. But the downside is that the file size will go for a toss as saving a 4 minute audio file in the .wav format will cost you about 20MB and above in terms of disk space. As an option to this, you can use the lossless codecs that will help you save a few MB’s per file. But overall, the file size will still be larger.
Next up is the part where protecting your audio files comes in. DRM (Digital Rights Management) cannot be applied for MP3 files but it can be for Ogg Vorbis (Experimental), WMP (Windows Media Player) and AAC . Therefore, if you are making an original recording, you can use AAC or WMP to restrict your recording from being pirated.
This section will only talk about software that are freely available and we are limiting ourselves to choosing between only four codecs. These are Windows Media Audio, MP3, Ogg Vorbis and AAC. We will be using applications that let us encode a single file into any of these formats. Please refer to the workshop at the end of this chapter for the results of the test that we have performed here.
From the workshop, it is quite clear that if you can compromise on the sound quality but want lower file sizes, then you will have to stick to MP3. If you are looking for a mid-sized file with decent audio quality, then opt for Ogg or AAC. For lossless encoding, only Windows Media Audio lets you do that and as seen the file size is not much different from the original .wav file.
From our listening tests, we concluded that the AAC and Ogg files were comparable in sound quality with each other while the MP3 file did feel to be missing something. Nevertheless, if you are not a fussy listener then you can make do with any of these codecs. For the fussy ones, stick to WMA or AAC Lossless.
Newer Formats
This is the age of digital music. Since the appearance of Compact Disc or CD, music has gone digital. In a nutshell, music is stored on a CD in bits or digital numbers which is then played back on a speaker. This process involves deciphering of the digital samples to analogue sound that drives the speakers using a Digital to Analog Converter (DAC). However, similar to the CD, there is a size limitation of the Audio CD.
This is where the newer formats such as DVD-Audio and Super Audio CD (SACD) step in. DVD-Audio aims to utilize the huge amount of space that it has to increase the sampling rate and to record data in surround sound rather than in stereo. Ditto for the SACD. Let us look at what these formats have in store for us.
DVD-Audio
DVD-Audio is yet another development of the DVD Forum, the group of companies that decides what should be considered a standard in the DVD arena in the the years to come. The main advantage of DVD-Audio over the standard CD is the impressive audio quality. The table ahead will illustrate the differences between these two formats and you can make out the difference by yourselves.
Next up is the part where protecting your audio files comes in. DRM (Digital Rights Management) cannot be applied for MP3 files but it can be for Ogg Vorbis (Experimental), WMP (Windows Media Player) and AAC . Therefore, if you are making an original recording, you can use AAC or WMP to restrict your recording from being pirated.
This section will only talk about software that are freely available and we are limiting ourselves to choosing between only four codecs. These are Windows Media Audio, MP3, Ogg Vorbis and AAC. We will be using applications that let us encode a single file into any of these formats. Please refer to the workshop at the end of this chapter for the results of the test that we have performed here.
From the workshop, it is quite clear that if you can compromise on the sound quality but want lower file sizes, then you will have to stick to MP3. If you are looking for a mid-sized file with decent audio quality, then opt for Ogg or AAC. For lossless encoding, only Windows Media Audio lets you do that and as seen the file size is not much different from the original .wav file.
From our listening tests, we concluded that the AAC and Ogg files were comparable in sound quality with each other while the MP3 file did feel to be missing something. Nevertheless, if you are not a fussy listener then you can make do with any of these codecs. For the fussy ones, stick to WMA or AAC Lossless.
Newer Formats
This is the age of digital music. Since the appearance of Compact Disc or CD, music has gone digital. In a nutshell, music is stored on a CD in bits or digital numbers which is then played back on a speaker. This process involves deciphering of the digital samples to analogue sound that drives the speakers using a Digital to Analog Converter (DAC). However, similar to the CD, there is a size limitation of the Audio CD.
This is where the newer formats such as DVD-Audio and Super Audio CD (SACD) step in. DVD-Audio aims to utilize the huge amount of space that it has to increase the sampling rate and to record data in surround sound rather than in stereo. Ditto for the SACD. Let us look at what these formats have in store for us.
DVD-Audio
DVD-Audio is yet another development of the DVD Forum, the group of companies that decides what should be considered a standard in the DVD arena in the the years to come. The main advantage of DVD-Audio over the standard CD is the impressive audio quality. The table ahead will illustrate the differences between these two formats and you can make out the difference by yourselves.
| Comparing DVD Audio and Compact Disc | ||
| Specification | DVD-Audio | CD |
| Audio Format | PCM | PCM |
| | 4.7Gb - Single layer | |
| Disk Capacity | 8.5Gb - Dual Layer | 650Mb |
| | 17Gb - Double Sided Dual Layer | |
| Channels | Up to 6 | 2 (stereo) |
| Frequency Response | 0 - 96kHz (max) | 5 - 20kHz |
| Dynamic Range | 144db | 96db |
| Sampling Rate - 2 channel | 44.1, 88.2, 176.4KHz or | 44.1kHz |
| Sampling Rate/Multi-channel | 44.1, 88.2KHz or | n/a |
| Sample Size (Quantization) | 12, 16, 20, or 24 bits | 16 bits |
| Maximum Data Rate | 9.6 Mbps. | 1.4Mbps |
Another factor is that for compatibility with DVD-Video players, DVD-Audio discs can also contain audio encoded using the Dolby Digital and/or DTS formats. Here is the catch. Say, you have a DVD-Audio disc which contains both PCM audio tracks and the same tracks encoded in either Dolby Digital or DTS. This disc, if inserted in a DVD-Audio player will playback the PCM tracks ONLY and ignores the encoded Dolby Digital or DTS tracks. This will happen even if the DVD-Audio player supports the DVD-Video standard. On the other hand, a DVD-Video player will only play the encoded Dolby Digital or DTS tracks and ignore the PCM tracks.
DVD-Audio discs can store PCM tracks as well as associate video and images to tracks making it an all-round experience for the end-user. Another factor that makes DVD-Audio discs more favorable to the RIAA (Recording Industry Association of America) is the copy-protection part. Most DVD-Audio discs have copy protection that makes it harder if not impossible to copy music of the discs.
However, there is a downside to all of this. It is the price of DVD-Audio discs, which are pretty much on the higher side compared to a regular Audio CD. The other factor is the low penetration of DVD-Audio discs in the market since they are not compatible with the billion plus CD players around the planet. Unless, you have a player that specifies that it can play DVD-Audio, you cannot use a DVD-Audio disc.
To combat this, the DVD Forum has come out with another format called the DVDPlus or DualDisc format. This is a disc with two sides. DVDPlus/DualDisc offer either DVD-Video or DVDAudio as well as CD content so it can include video, interactivity, stills and text as well as audio. Such types of discs are also called as Hybrid Discs.
Codecs
By the mid ‘90s, usage of internet increased manifold and with the dawn of the new millennium certain radical changes were happening in the world of digital audio. Audio CDs, by far, were in charge and everybody and anybody had a CD player. Nonetheless, there was one fundamental problem. First, CD’s scratch easily and second, one cannot transport a CD over the net physically.
With the Internet slowly becoming the hub of all entertainment, it was necessary to look for other, more cost effective options for a good audio-visual experience that did not hog bandwidth yet provided decent quality-both in terms of audio and video. This was the basic idea that facilitated the inception of audio and video codecs.
A “codec” can be defined as the combination of two words-Encoder and Decoder. These encoders and decoders can be either hardware or software, but we will only talk about the software codecs. Before we actually delve into the world of software codecs, let us get our basics on digital music right.
When we talk about a software codec, it is a software program containing an algorithm to compress and then decompress data. For instance, if an MP3 file is encoded at a bit-rate of 128K from a source file that is 20MB in size (uncompressed), then the resulting file would be approximately 2MB in the compressed form, going by the 11:1 compression ratio, which the MP3 codec compresses at. Talking about compression ratios, it is the ratio of the size of the original uncompressed audio file and the compressed resulting audio file.
Next up are the two categories of codecs-lossless and lossy respectively. An example of a lossless codec is WMA and a lossy codec is MP3. The term "lossless" means that the compressed file is identical to the original file in all aspects. If you take a spectrum analysis of the original file and compare it with the compressed file, the resultant spectrum will be one single line with all the peaks and valleys and spikes matching each other to the ‘T’. If not, it means there is some loss that is taking place during compression.
Encoding music using a lossless codec takes a lot of time and does not compress music a great deal. A 10MB file will be compressed to a maximum of about 7MB using WMA (Windows Media Audio 9). There are other codecs such as AAC (Advance Audio Codec) and Ogg Vorbis, which we will talk about in a little while. But before we talk about these codecs, let’s talk about the MP3 codec, the one piece of software that started it all.
An apt example of a lossy codec is MP3. The MP3 codec uses the "perceptual coding" technique. The Fraunhoffer institute in Germany, along with Prof. Dieter Seitzer of the University of Erlangen, developed an algorithm that was standardised as the ISO-MPEG Audio Layer-3.
MP3 is far more popular than any other format or codec as it allows for exceptionally small file sizes without much difference in the rendered audio quality. However, there is a large difference statistically between the original uncompressed music file and the resultant MP3 file. This is where perceptual coding steps in. The trick that “perceptual coding” uses, is it removes information from a particular audio or video file. Users cannot "perceive" the loss of higher or lower frequencies that are present in the original file but are cut off in the compressed MP3 file. The overall music quality does not suffer but the file size reduces due to such loss of information and hence MP3 is called a "lossy codec".
If you run a spectrum analyser on a compressed MP3 file and compare it with the original uncompressed recording, you will find that there is no “one-to-one” match of the two spectrums. Very high or very low frequencies which the codec thinks is beyond audible perception of the user are cut off.
Codecs such as AAC, Ogg Vorbis etc. use different algorithms. For instance, AAC is based on the MPEG-2/-4 standard and can use be used as a lossless or lossy compression technique as required. So which audio codec is right for you? Read on to find out.
With the Internet slowly becoming the hub of all entertainment, it was necessary to look for other, more cost effective options for a good audio-visual experience that did not hog bandwidth yet provided decent quality-both in terms of audio and video. This was the basic idea that facilitated the inception of audio and video codecs.
A “codec” can be defined as the combination of two words-Encoder and Decoder. These encoders and decoders can be either hardware or software, but we will only talk about the software codecs. Before we actually delve into the world of software codecs, let us get our basics on digital music right.
When we talk about a software codec, it is a software program containing an algorithm to compress and then decompress data. For instance, if an MP3 file is encoded at a bit-rate of 128K from a source file that is 20MB in size (uncompressed), then the resulting file would be approximately 2MB in the compressed form, going by the 11:1 compression ratio, which the MP3 codec compresses at. Talking about compression ratios, it is the ratio of the size of the original uncompressed audio file and the compressed resulting audio file.
Next up are the two categories of codecs-lossless and lossy respectively. An example of a lossless codec is WMA and a lossy codec is MP3. The term "lossless" means that the compressed file is identical to the original file in all aspects. If you take a spectrum analysis of the original file and compare it with the compressed file, the resultant spectrum will be one single line with all the peaks and valleys and spikes matching each other to the ‘T’. If not, it means there is some loss that is taking place during compression.
Encoding music using a lossless codec takes a lot of time and does not compress music a great deal. A 10MB file will be compressed to a maximum of about 7MB using WMA (Windows Media Audio 9). There are other codecs such as AAC (Advance Audio Codec) and Ogg Vorbis, which we will talk about in a little while. But before we talk about these codecs, let’s talk about the MP3 codec, the one piece of software that started it all.
An apt example of a lossy codec is MP3. The MP3 codec uses the "perceptual coding" technique. The Fraunhoffer institute in Germany, along with Prof. Dieter Seitzer of the University of Erlangen, developed an algorithm that was standardised as the ISO-MPEG Audio Layer-3.
MP3 is far more popular than any other format or codec as it allows for exceptionally small file sizes without much difference in the rendered audio quality. However, there is a large difference statistically between the original uncompressed music file and the resultant MP3 file. This is where perceptual coding steps in. The trick that “perceptual coding” uses, is it removes information from a particular audio or video file. Users cannot "perceive" the loss of higher or lower frequencies that are present in the original file but are cut off in the compressed MP3 file. The overall music quality does not suffer but the file size reduces due to such loss of information and hence MP3 is called a "lossy codec".
If you run a spectrum analyser on a compressed MP3 file and compare it with the original uncompressed recording, you will find that there is no “one-to-one” match of the two spectrums. Very high or very low frequencies which the codec thinks is beyond audible perception of the user are cut off.
Codecs such as AAC, Ogg Vorbis etc. use different algorithms. For instance, AAC is based on the MPEG-2/-4 standard and can use be used as a lossless or lossy compression technique as required. So which audio codec is right for you? Read on to find out.
Thursday, 15 March 2007
Digital Audio
The human body responds to five basic stimuli and one of them is sound. From time immemorial, man has been creating music, which, like man, has evolved with the passage of time. From Edison’s Phonograph to Steve Jobs’ Apple iPod, here we will talk about everything audio and also give you an insight into the world of digital audio.
Evolution
From the time we homo-sapiens learned to understand sound and create it, we have also played around with it. Be it anywhere on this planet, irrespective of religion and caste, all stories have had music associated with them. Fables usually had a bard singing for his damsel, or the Pied Piper luring the children with his captivating tunes. Music is everywhere and with music comes sound.
Although we know about Bach, Beethoven and Tansen, none of their original renditions are available to us as played by them. That’s because there were no methods of recording anything at the time, except in the form of written musical notes. Thomas Edison was someone who changed the scene with his invention of a device that could record and playback sounds.
Christened the phonograph, this invention came about as a byproduct of another experiment he was conducting to develop the Morse code. The technology that led to the phonograph came from developments that Edison made in the telegraph and telephone.
At the time, Edison was experimenting with how a moving diaphragm that was linked to a coil could produce a voice-modulated signal. Meanwhile, he was also experimenting with a telegraph repeater that was simply a device that used a needle to indent paper with the dots and dashes of the Morse code.
From these two ideas came the concept of attaching the stylus from a telegraph repeater to the diaphragm in the mouthpiece of a telephone. The first test in July 1877 involved a sheet of paper pulled under the needle, mechanically coupled to a diaphragm, as he shouted into the mouthpiece. This however, didn’t work but it did produce an unrecognisable sound, which was enough to prove that the concept was right.
Edison then went on to improvise on this and replaced the paper sheet with tin foil. The tin foil was mounted on a cylinder, and the cylinder was turned via a hand crank during recording and playback. Edison turned the crank and spoke the first recorded words. “Mary had a little lamb, its fleece was white as snow, and everywhere that Mary went, the lamb was sure to go”. This was the first recorded sound in the history of audio.
This, however, was just the start of a revolution in the realm of audio recording. Edison made loads of money on this invention as did his competitors. However, the storm had just begun! Soon, the market was flooded with devices such as the Dictaphone (Columbia) and Ediphone (Edison Company), though, there was another device that we would remember from our childhood that grabbed everybody’s attention and made music available to the masses.
The Gramophone
While the phonograph was being developed, a German immigrant by the name of Emile Berliner of Washington, D.C., filed and patented a talking machine that recorded and played back sound in 1888.
The technology that Emile used was similar to the Dictaphone/Ediphone, however, there was one radical difference: instead of using a cylinder, Berliner used a flat recording disc and a stylus that cut a spiral groove while the stylus in the cylinder moved up and down in a vertical cut recording format (known also as the "hill-anddale" vertical cut) to record the audio.
The main advantage of such a medium was that thousands of records could be inexpensively pressed from just one ‘master’ record. The Gramophone soon became a worldwide standard and is in existence even today. Although the wax discs have been replaced by vinyl LP’s, this device is a treasure. All this development was happening in the late 1800’s and early 1900’s. By 1930, with more technological advances, Wire Recorders became available. However, these were extremely expensive (like all new devices) and were affordable only to the rich and famous.
The Audio Tape
The ubiquitous audio tape made its appearance sometime after Wire Recorders. It soon became the media of choice to record on. Although the audio tape was still in its formative stages, it showed a lot of promise. Open reel to reel was the predominant format since the time of inception to the early ‘80s when digital audio started to make its appearance.
Depending on the dimensions of the reel and the tracks available for recording, users could store up to 12 hours of recording on it. The Standard Audio Cassette, or the Compact Cassette as it is called, is the final and completely refined version of the reel Audio tape. Philips developed this cassette in 1962 for their new dictation phone series and the Compact Cassette was never meant to be anything else other than recordable media for these machines.
However, its compact size, reliability, low manufacturing costs and Hi-Fi stereo capability ultimately led to wide market acceptance. The original audiotapes were made of Ferric Oxide, but later improvements such as Chromium dioxide and other metal combination tapes were used to greatly improve sound quality and reduce noise.
However, recording equipment, which could record on such media, was expensive and since Chrome tapes had different bias frequency requirements, it also needed more sophisticated recording equipment. These machines also used various Noise Reduction technologies, of which Dolby Noise Reduction technology remains the most used till date.
With the introduction of the compact cassette, it was widely used to archive old vinyl records. The audio cassette is still going strong about 43 years after birth but the compact disc or CD as we know it today, was what made the dent in its armour. With the advent of CDs, the digital wave was well and truly on its way.
The Digital Wave
Philips and Sony were jointly responsible for inventing and bringing the CD to the masses. Research and development started on the CD back in the ‘70s but the finished product debuted only in 1982. As usual, it took quite some time for it to be popular because of prohibitive costs. But the CD was extensively marketed and no one could deny it’s exceptional sound quality and portability, which far outweighed the high cost for many consumers. With the efficiencies of mass production and affordable pricing, CD became the medium of choice by the end of ‘80s.
Mass acceptance of the CD ended the long running reign of LP records. Skips, crackles, pops, wow, flutter, surface noise, all synonymous with vinyl and magnetic cassette tapes, were now a thing of the past. With plummeting prices and high media reliability software companies soon began distributing software on CDs. Companies such as America Online (AOL) did numerous mass mailings of their online software. And what happened to CDs that went bad? Well, people coined a new term-coasters-that referred to CDs that were unusable and were used for everything else other than their intended purpose.
Continued product development led to the CD-R and CD-R/W formats for both audio and data. Today’s higher sampling rates and bit depths have resulted in improved fidelity. The CD with its 44.1 kHz sampling rate at 16-bit depth still reigns as the audio champ, although newer technologies, catering specifically to users who want a more aural, more "being there" experience have evolved.
Technologies such as Super Audio CD, again a Philips-Sony invention and DVD-Audio are slowly doing to the CD, what the CD did to the vinyl. These newer technologies offer higher bit rates and frequencies, which, for an audiophile, is literally pleasure to the ears. We will talk about these formats later.
As mentioned earlier, the CD format was an exceptional format for both audio and data storage but with plummeting prices and more competition, mediocrity inevitably crept into the quality of the media. Also, with the penetration of the Internet in the ‘90s, another revolution was silently taking form in the digital era.
Nevertheless, before we talk about the digital revolution in its truest sense, there were other worthy adversaries. Prominent amongst these was the Digital Audio Tape or DAT for short. This technology was introduced in 1987 but was limited to the professional community and some consumers. The primary reason for this was the cost (again!). From the perspective of studios, DAT offered digital storage capabilities at relatively low costs, but these costs were too high for the masses. Another factor that made DAT recorders favourable for studios was the fact that it was regarded as a professional digital format used for original mastering and therefore bypasses the SCMS (Serial Copy Management System), allowing multi-generation, lossless digital recordings.
Sony introduced their proprietary MiniDisc (MD) format in 1998. This was supposed to be revolutionary since the size of the MiniDisc was much smaller than the regular CD but the quality of the recording was much superior and you could store up to twice the amount of content as compared to a standard CD (74 minutes). However, the MiniDisc never really gained mass acceptance despite its obvious advantages. But this was just the lull before the storm.
Evolution
From the time we homo-sapiens learned to understand sound and create it, we have also played around with it. Be it anywhere on this planet, irrespective of religion and caste, all stories have had music associated with them. Fables usually had a bard singing for his damsel, or the Pied Piper luring the children with his captivating tunes. Music is everywhere and with music comes sound.
Although we know about Bach, Beethoven and Tansen, none of their original renditions are available to us as played by them. That’s because there were no methods of recording anything at the time, except in the form of written musical notes. Thomas Edison was someone who changed the scene with his invention of a device that could record and playback sounds.
Christened the phonograph, this invention came about as a byproduct of another experiment he was conducting to develop the Morse code. The technology that led to the phonograph came from developments that Edison made in the telegraph and telephone.
At the time, Edison was experimenting with how a moving diaphragm that was linked to a coil could produce a voice-modulated signal. Meanwhile, he was also experimenting with a telegraph repeater that was simply a device that used a needle to indent paper with the dots and dashes of the Morse code.
From these two ideas came the concept of attaching the stylus from a telegraph repeater to the diaphragm in the mouthpiece of a telephone. The first test in July 1877 involved a sheet of paper pulled under the needle, mechanically coupled to a diaphragm, as he shouted into the mouthpiece. This however, didn’t work but it did produce an unrecognisable sound, which was enough to prove that the concept was right.
Edison then went on to improvise on this and replaced the paper sheet with tin foil. The tin foil was mounted on a cylinder, and the cylinder was turned via a hand crank during recording and playback. Edison turned the crank and spoke the first recorded words. “Mary had a little lamb, its fleece was white as snow, and everywhere that Mary went, the lamb was sure to go”. This was the first recorded sound in the history of audio.
This, however, was just the start of a revolution in the realm of audio recording. Edison made loads of money on this invention as did his competitors. However, the storm had just begun! Soon, the market was flooded with devices such as the Dictaphone (Columbia) and Ediphone (Edison Company), though, there was another device that we would remember from our childhood that grabbed everybody’s attention and made music available to the masses.
The Gramophone
While the phonograph was being developed, a German immigrant by the name of Emile Berliner of Washington, D.C., filed and patented a talking machine that recorded and played back sound in 1888.
The technology that Emile used was similar to the Dictaphone/Ediphone, however, there was one radical difference: instead of using a cylinder, Berliner used a flat recording disc and a stylus that cut a spiral groove while the stylus in the cylinder moved up and down in a vertical cut recording format (known also as the "hill-anddale" vertical cut) to record the audio.
The main advantage of such a medium was that thousands of records could be inexpensively pressed from just one ‘master’ record. The Gramophone soon became a worldwide standard and is in existence even today. Although the wax discs have been replaced by vinyl LP’s, this device is a treasure. All this development was happening in the late 1800’s and early 1900’s. By 1930, with more technological advances, Wire Recorders became available. However, these were extremely expensive (like all new devices) and were affordable only to the rich and famous.
The Audio Tape
The ubiquitous audio tape made its appearance sometime after Wire Recorders. It soon became the media of choice to record on. Although the audio tape was still in its formative stages, it showed a lot of promise. Open reel to reel was the predominant format since the time of inception to the early ‘80s when digital audio started to make its appearance.
Depending on the dimensions of the reel and the tracks available for recording, users could store up to 12 hours of recording on it. The Standard Audio Cassette, or the Compact Cassette as it is called, is the final and completely refined version of the reel Audio tape. Philips developed this cassette in 1962 for their new dictation phone series and the Compact Cassette was never meant to be anything else other than recordable media for these machines.
However, its compact size, reliability, low manufacturing costs and Hi-Fi stereo capability ultimately led to wide market acceptance. The original audiotapes were made of Ferric Oxide, but later improvements such as Chromium dioxide and other metal combination tapes were used to greatly improve sound quality and reduce noise.
However, recording equipment, which could record on such media, was expensive and since Chrome tapes had different bias frequency requirements, it also needed more sophisticated recording equipment. These machines also used various Noise Reduction technologies, of which Dolby Noise Reduction technology remains the most used till date.
With the introduction of the compact cassette, it was widely used to archive old vinyl records. The audio cassette is still going strong about 43 years after birth but the compact disc or CD as we know it today, was what made the dent in its armour. With the advent of CDs, the digital wave was well and truly on its way.
The Digital Wave
Philips and Sony were jointly responsible for inventing and bringing the CD to the masses. Research and development started on the CD back in the ‘70s but the finished product debuted only in 1982. As usual, it took quite some time for it to be popular because of prohibitive costs. But the CD was extensively marketed and no one could deny it’s exceptional sound quality and portability, which far outweighed the high cost for many consumers. With the efficiencies of mass production and affordable pricing, CD became the medium of choice by the end of ‘80s.
Mass acceptance of the CD ended the long running reign of LP records. Skips, crackles, pops, wow, flutter, surface noise, all synonymous with vinyl and magnetic cassette tapes, were now a thing of the past. With plummeting prices and high media reliability software companies soon began distributing software on CDs. Companies such as America Online (AOL) did numerous mass mailings of their online software. And what happened to CDs that went bad? Well, people coined a new term-coasters-that referred to CDs that were unusable and were used for everything else other than their intended purpose.
Continued product development led to the CD-R and CD-R/W formats for both audio and data. Today’s higher sampling rates and bit depths have resulted in improved fidelity. The CD with its 44.1 kHz sampling rate at 16-bit depth still reigns as the audio champ, although newer technologies, catering specifically to users who want a more aural, more "being there" experience have evolved.
Technologies such as Super Audio CD, again a Philips-Sony invention and DVD-Audio are slowly doing to the CD, what the CD did to the vinyl. These newer technologies offer higher bit rates and frequencies, which, for an audiophile, is literally pleasure to the ears. We will talk about these formats later.
As mentioned earlier, the CD format was an exceptional format for both audio and data storage but with plummeting prices and more competition, mediocrity inevitably crept into the quality of the media. Also, with the penetration of the Internet in the ‘90s, another revolution was silently taking form in the digital era.
Nevertheless, before we talk about the digital revolution in its truest sense, there were other worthy adversaries. Prominent amongst these was the Digital Audio Tape or DAT for short. This technology was introduced in 1987 but was limited to the professional community and some consumers. The primary reason for this was the cost (again!). From the perspective of studios, DAT offered digital storage capabilities at relatively low costs, but these costs were too high for the masses. Another factor that made DAT recorders favourable for studios was the fact that it was regarded as a professional digital format used for original mastering and therefore bypasses the SCMS (Serial Copy Management System), allowing multi-generation, lossless digital recordings.
Sony introduced their proprietary MiniDisc (MD) format in 1998. This was supposed to be revolutionary since the size of the MiniDisc was much smaller than the regular CD but the quality of the recording was much superior and you could store up to twice the amount of content as compared to a standard CD (74 minutes). However, the MiniDisc never really gained mass acceptance despite its obvious advantages. But this was just the lull before the storm.
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