Add a comment. Active Oldest Votes. Improve this answer. Petr Abdulin Petr Abdulin Roman R. BrokenGlass BrokenGlass k 27 27 gold badges silver badges bronze badges. Is there a way to see if a video stream is present? Does this video stream have some identification bits?
Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. But those same 9 songs might only use up 50 megabytes once compressed. With lossless compression, instead of deleting extra blocks, the redundant blocks are removed and replaced with instructions.
For example: In the chart below, you'll see that once our audio file is compressed into a lossless format, two blocks are now represented by one block with the number two. Three blocks are represented by one block with the number three, and so on. When your music player reads the compressed file, it processes the instructions and rebuilds the original file with no loss of the original audio data. It gives you a much smaller file size while retaining the highest possible audio quality.
The benefit of lossless compression is this retention of audio quality and a reduced file size. The downside is that the file sizes are still larger than with lossy compression, and not all music players support lossless file formats.
FLAC is an acronym for Free Lossless Audio Codec and is a lossless audio format that allows reduced file size with no cost to audio quality. FLAC files are compressed in a way that does not reduce the audio quality, making it one of the best formats available for archiving your music. FLAC was introduced in as an open-source file type and has grown to one of the most popular audio file formats today. Because it is one of the most popular lossless formats, most modern devices support FLAC playback.
The file format has evolved since its initial launch, but has continually retained the WMA file extension. The WMA format is similar to the MP3 format and compresses the audio file in a similar way that leads to a reduction in file size at the cost of reduced audio quality. Because this format is not as widely supported as MP3, there is no advantage to choosing this file type. The MP3 format was originally released all the way back in , and has been steadily gaining in popularity ever since the dot com boom of the s.
WMA was developed in the 90s as a better version of MP3. WMA stored compressed data just like MP3, but it managed to have better sound quality.
Due to this, WMA gained popularity among people who downloaded music for listening. This is because of the compression method used in WMA that stores large compressed files which may not be compatible with old devices.
WMA can have a maximum frequency response of approximately 18 kHz. This means that some sounds which were noticeable in the original audio file will get suppressed during encoding. Moreover, WMA cannot create seamless loops. On the other hand, WMA files were created for downloading and listening to music. However, contrary to popular belief, WAV audio format can store compressed audio files like MP3 as well.
The following overviews have therefore become more of a history of the earlier formats and codecs. For up-to-date information about the latest and greatest, you should look elsewhere. Video codecs have come a long way. Between raw uncompressed video, the only thing available in the earliest days of digital video, and the latest most advanced codecs, there is easily a factor of or even better when it comes to the reduction in storage space needed to represent video at a quality level with no obvious visual degradation.
The following list in roughly historical ordering gives a bit of a hint of how this is possible. Audio compression does not have the advantage that the data consists of very repetitive structures in 2 or even 3 dimensions, which makes it harder to compress.
The best compression schemes actually exploit limitations of the human auditory system to discard information in a way that is usually not noticeable. For the best codecs currently available, this has led to a reduction in storage requirements of almost a factor 10, a far cry from the factor achieved in video compression but still a lot better than nothing. Next to confusing a container format with a codec, another misconception that used to be prevalent, was the confusing of a media format with a media player.
This confusion luckily has become less commonplace since the marketplace for digital media lost a lot of its monopolistic nature and video playback is now a standard feature of any mobile device. However, there is no technical reason why today a certain player couldn't open and play a different format than its native format.
Again, the only barriers against this are legal. Many of these barriers have broken down thanks to the proliferation of media formats on the internet. VLC and MPlayer are open-source players which intend to support as many formats as possible. It is this kind of convenience that has caused players like these to have mostly displaced the native players like QuickTime or Windows Media Player.
There are only two obstacles that can prevent a player from playing a certain file: the codecs or DRM. Codecs are the reason why one AVI or MOV file plays fine in your copy of MPlayer while other files with the same extensions don't: if your player doesn't support the codec used in the file, it won't play.
Detailed specifications required to implement your own complete WMV decoder were not publicly available. One had to either pay a licence fee to Microsoft or resort to tactics like reverse engineering to be able to play WMV outside of the Windows framework.
A more devious tactic was to tap into copied Windows Media software libraries, which was a legally very dubious practice. This means that any variants of WMV that have not been reverse engineered yet, cannot be played on a different platform than the ones for which WM libraries are available.
The same goes for QuickTime's Sorenson codec. I'm not sure if all its variants have been reverse engineered yet, or whether the rights and specifications have been released to the public, and to be honest nobody probably cares because this codec has been largely displaced by H.
DRM Digital Rights or Restrictions Management, depending on whether you're a lawyer or user is the other reason why you can only play certain files in a certain player. The AAC audio files from the iTunes music store also originally had a layer of DRM added to them until the introduction of iTunes Plus, although the restrictions were not that strict.
It is clear that from a user's point of view, DRM is totally undesirable and it seems most companies have finally started to understand this. If one simply makes it easy enough for customers to stream media at a reasonable cost, then it no longer makes sense to keep investing in increasingly watertight anti-theft technology to prevent copying of the stream at all costs. It suffices to make the security good enough that the subjective cost of capturing and illegally redistributing the stream is considerably higher than the actual cost of getting the stream flowing legally in an easy-to-use interface on any device of choice.
This is one of the reasons behind the success of companies like Netflix. On the Windows platform and also to a lesser degree on Linux, QuickTime was rather unpopular for different reasons. That's not something Apple can do much about. However, Apple itself has also been making a few stupid mistakes.
First of all, QuickTime on Windows became notorious for bad stability. Of course it would have been easy for Microsoft to make QuickTime crash on random occasions 1b.
But even if we put all paranoia aside and look at how stable current versions are, there are still some major issues. Since version 3 of QuickTime, there were two variants that reek of involvement from an overly active marketing team: standard QuickTime and QuickTime Pro.
The first only allows to play movies, and you need to pay for the latter. However, Apple was stupid enough to include a nagging screen in the standard version which always popped up when opening the QT Player, until you upgraded to QuickTime Pro. That's one hell of a way to annoy people! Luckily the pop-ups were removed in newer versions, but they are still burned into peoples' collective memory. Worse however, is that for a very long time full screen playback was restricted to the Pro version only.
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