Does video quality of "video only"+audio have difference with ALREADY merged video

[StaringtheStar]

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Question

YouTube-dl provides multiple formats of videos.
For instance, when I download 720p video, I could select format 22(already merged), but I could select 136 and merge it with other audio formats such as 140.

I want to compare the amount of "LOSS" of videos.

• Already merged format: -f 22
• Video only format: -f 136
• post-merged video format(Video only + audio): -f 136+140

If there are any data or ways to check this, please let me know.

[dstftw]

Obviously you won't get files byte to byte equal but they will likely be somewhat close.

[StaringtheStar]

@dstftw
Do you mean they are almost same so it is meaningless to talk about the difference of loss amount?