Technical

[timea-techgirl]

Hello, I have been reviewing many youtube/video downloaders to finally write a blog post on a major site to let people know which youtube downloader is the best of all.

This is the video link I tested:
http://www.youtube.com/watch?v=UMkSPXHPG5E

I used many youtube downloaders to download a specific video for testing purposes. I wanted to download the best quality without re-encoding or converting, which is 1080p for this particular video. All youtube downloaders downloaded the audio file as "m4a" with 44Khz. But one of the
youtube downloaders downloaded the audio file as "webm" audio which is 48Khz. So, I'm very confused and curious about this. I don't know what's going on. I want to find an answer to finalise my blog post.

1. Which audio source is the original? m4a or webm audio?

2. Why are most downloaders using m4a and not webm audio?

3. How to download the original video and audio in original format the uploader uploaded to youtube?

Please enlighten me. Thank you.

[dstftw]

1. Both original (in terms of media files served by YouTube). -F to list all original formats available.
2. Ask them why.
3. Probably you can't do that at all since YouTube does not provide author-original formats but only reencoded to formats that YouTube serves.

[timea-techgirl]

Thanks. What does (best) mean? youtube-dl shows best for 720p. Can you tell me what that means?

They said webm doesn't play in players even if it is better in quality. Is that right?

Why are some 720p videos greater in size than muxed 1080p video and audio files?

[Hrxn]

Why are some 720p videos greater in size than muxed 1080p video and audio files?

Theoretically possible, but very unlikely..
Do you have an example?

They said webm doesn't play in players even if it is better in quality. Is that right?

All current players should handle .webm. VideoLAN definitely does.

[dstftw]

best is best quality file served as single file (most of the time it's worse that bestvideo+bestaudio). It shows best because it meets aforementioned semantics.

They said webm doesn't play in players even if it is better in quality. Is that right?

webm doesn't play in players? What a nonsense?

Why are some 720p videos greater in size than muxed 1080p video and audio files?

Technically, filesize is not a measure of quality when comparing h264 and vp9.

[timea-techgirl]

This is an example:
https://www.youtube.com/watch?v=MqfesKdiXtc

Yes, I know. Webm plays fine, both audio and video webm files. Do you prefer m4a or webm audio?

If I want the best quality video and audio, what do you prefer? What command should I use?

[dstftw]

youtube-dl prefers formats according to metadata provided (bitrate, filesize and so on).
Read FAQ on format selection.

[timea-techgirl]

Thanks. I read it. So, for the above example video, webm is the best.

I typed,
youtube-dl https://www.youtube.com/watch?v=MqfesKdiXtc
and it started downloading a 90.9mb file size which is not listed among the formats. Which file is this?

If I type,
youtube-dl -f bestvideo+bestaudio https://www.youtube.com/watch?v=MqfesKdiXtc
it downloads the best webm files. After muxing, will it save it as webm? I don't want to re-encode.

[Hrxn]

If I want the best quality video and audio, what do you prefer? What command should I use?

-f bestvideo,bestaudio

Two different streams, two different files.

No need to encode, just mux/merge.

[timea-techgirl]

Do you prefer ffmpeg or avconv?

Is there a GUI of youtube-dl?

What is the simple merge command for ffmpeg without re-encoding?