How to capture YouTube at Max Quality. (This is educational and not meant for "copyright Infringement")
The Goal of any qudio recording is Purity. This is my method for preserving bit perfect from the small limited audio quality from YouTube.
Things NOT to do As in 2013:
1. Do not Use YouTube to MP3 converted, or any convertion.
2. Do not use any other codec than H.264 AAC as the others codecs the audio is very poor on youtube servers.
3. Do Not capture from YouTube's browser player.
These are my rough steps:
1. Download the entire H.264 video at MAX quality, lucky best if you get 720p or "Original" which is AAC LC VBR 192kbs plus. This can be done through many methods & software, main thing directly capture the video file from youtube with no conversion.
2. DEMUX (demultiplexing not convert) the AAC LC audio track from the H.264 video file, this can be done through many method MP4Box being the most well known.
3. Repack the AAC LC file into a ".M4A" file which will provide compatibility and metadata.
4. Add Meta Data & album art into .M4A file, Finnished.
In my method at no point was the audio file from the Youtube Video converted thus no corruption occured. From my experience even using the best H.264 hardware converting the ACC LC still is degraded from the original. Remember Purity.