Quality of videos stored on YouTube.
As you know, video on YouTube is stored in various qualities. This means that the quality of the audio track is different. By default, the program downloads a video stream with lirgest size. Assuming that this video stream contains the best audio quality. But often different video streams contain audio tracks whose quality the same or similar. While their sizes are different. Differences in size can be significant. Especially if the video contains streams in HD video quality. It means that the download time could increase significantly. This state can be changed in preferences. To do this, open the Preferences dialog box and select the Download tab. Check Use format priority list and 2 lists will be enabled. You can drag and drop formats from one list to another. The left list contains formats which will be selected to download the video stream according to priority (from top to the bottom). While the right list contains formats which will be ignored.
For example, I've removed all HD formats except one. Which is the lowest among HD and contains AAC audio stream. Also, I've removed all WebM formats (WebM contains audio in OGG format). And removed the lowest 144p 3GP format. This variant can be suitable for the most of cases.
Choosing audio format and its settings.
YouTube to MP3 Converter supports saving to MP3, M4A (AAC) and OGG format. Because all videos on YouTube stores audio tracks in one of these formats.
You can set up to save audio in original quality. It means that if will saved without additional conversion. You can check all formats (MP3, M4A and OGG). In these case downloaded audio file will be saved in the same format and quality as in video stream selected according priority format list (as has been described above).
But there are many devices which doesn't support OGG audio format while supports MP3 and M4A (AAC). In this case you may disable OGG from Keep original stream options. And you may choose default audio format and its settings which will be used if downloading video stream contain OGG audio format. Select between MP3 and M4A. About selecting bitrate we will talk a little later.
For example, iTunes supports M4A and MP3 formats. Then settings like this will be good if you need to save audio in original quality.
If you device supports MP3 only, then you can uncheck M4A also and left MP3 format only. And you will need to set up default MP3 format settings for conversion if source video stream doesn't contain MP3 audio track.
We have talked about saving audio in original quality. It can be helpful if the most of videos you are downloading are in low quality and you don't want to waste the disk size. Or you need to save in best quality as possible and want to minimize the size of saved file. Because conversion from lower quality to higher will cause increase the size of saved file without improving audio quality.
But if you need to save to MP3 format only (or another) with predefined quality then you may uncheck all formats from Keep original stream. Then select audio format and its settings which you need
For example, if you have audio player which supports MP3 format only. And it has low memory (disk) size. Then you can select MP3 format, CBR and 128kbps. Because, These settings are a good balance between speed and small file size. The higher bitrate means higher size of saved file.
If you need a better quality without wasting disk size then you could consider 192kbps or 224kpbs.
If video your are saving is not musical and contains voice (speech) then we suggest you to consider 96kbps of 64kbps.
As about MP3 VBR (variable bitrate) mode, 0 - means highest quality. It is suitable to save music. 9 - means lowest quality (lowest file size). It can be used to save lectures.
The most video streams on YouTube contains AAC audio streams. And if your player supports M4A (AAC) we can recommend you to save in this format (also, saving in original quality). Supports bitrates from 48kbps to 152kbps. As in MP3 format, higher bitrate means higher quality and higher file size. 128kbps is a reasonable balance of quality and size.
You can read more about YouTube video and audio formats in Wikipedia.