Sound quality is generally worse in videos than original music file/mp3?

For instance, you wanna listen to a music (i mean without sequentially shown images, concert scenes etc.) on youtube and looking for a pure music one. Lets say, There is a link belongs to "Another Brick In The Wall" by Pink Floyd showing the video clip, whereas, you can see another link only the song with lyrics in the form of a video.

Audio quality in the first option is usually worse than the second one. What's the reason for this?

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WafflesAndRootbeer

thedrama wrote: »

For instance, you wanna listen to a music (i mean without sequentially shown images, concert scenes etc.) on youtube and looking for a pure music one. Lets say, There is a link belongs to "Another Brick In The Wall" by Pink Floyd showing the video clip, whereas, you can see another link only the song with lyrics in the form of a video.

Audio quality in the first option is usually worse than the second one. What's the reason for this?

There is no reason for it. One is a copy of a music video, usually a low-quality recorded rip and the other uses a CD track. On top of that, YouTube loads the lowest quality streaming version of either one by default.

Heero

You have to go by both the source and the compression youtube adds. The source for a video that is pure music is generally gonna be flac, or the cd file, or a high quality mp3, like the previous poster mentioned. With a music video, they would be taking whatever came with the music video. If it is a fan made music video, then maybe they are using the same quality source material as the other though.

Also, youtube does its own conversion and compression. 240p, 360p, 480p, 720p, 1080p. It not only re-encodes the video, but also the sound. Watching at the highest available quality will make the audio sound as close to what you uploaded as possible.

DevilWAH

WafflesAndRootbeer wrote: »

There is no reason for it. One is a copy of a music video, usually a low-quality recorded rip and the other uses a CD track. On top of that, YouTube loads the lowest quality streaming version of either one by default.

I agree this is the main cause. Many videos already have encoded music (especially if copied from tv where the audio is heavily encoded), so encoding them a second time (even if using a higher bitrate) will further decrees the quality. Music encoded from the CD however is from a higher quility source to start with, and the people encoding are generally looking to retain as much quality as possible.

Most people will simply run a video file through a encoder to reduce the size to fit on a web page, which as I say will re-encode both video and audio, often to different formats for both. A better approach if you have the time is to not re-encode the audio if it is already in a suitable format and only do the video stream.

GSpot Codec Information Appliance is a great little tool that will show you what encoding is used for a video file (or audio), both the audio and video streams. if you drag and drop a few internet videos and audo files on it look and see what quality the audio is and what format.

And while you are correct most music videos how lower quality audio than the audio only track. this is purely down to the users or method to encode them to save bandwidth. IF you know what you are doing and have the original music video file with a high quality audio track that you need to encode to reduce its size, you can chose if you want to favour video or audio quality.

The common practice is to encode the audio at a lower bit-rate than you would an audio audio only track and retain the picture quality. there is no written rule, but back in the day when 5mb took a long time to down load, you compressed files as much as possible, and audio can take much more compression and still be acceptable than video.

For example if you think a standard mp3 file is 192kbs or 320kbs for near CD quility. Audio books are often encoded at only 16kbs and it is hard to ell the difference with spoken word. so it was not uncommon to encode audio on videos at 96kbs, played along side a video it was accatable and it was not until you compared it against the 192kbs version that you could really tell the difference.

Video is no where near as forgiving, and there is a sharp drop in quality below specific bit rates and resolutions (varies depending on the format you use).

So it was always a case of get the video right and then squease the audio to fit after (generally trying to fit it on a 700mb CD), And this seems to have stuck for on line video, with most programs defaulting to a low quality audio bit rate.

It is getting better and we do see a lot more near-cd quility video clips around.

I should add that you-tube will also be keen to keep the compression as high as possible for storage reasons. 48hours of video are uploaded every minute. Lets assume that all this videos is re-encoded to have mp3 audio at 320kbs bit rate.

That = about 6.5Gbytes of audio data...

so that's about 8.5 tybytes a day!

if they re-encode every upload to 128kbs that's saving over 4Tbytes..

So it is in their intrest, to downgrade the quality to some thing that is both acceptable to the watcher, and to their storage solution.

thedrama

Thanks to all for your interest.