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Audio being re-encoded when using subtitles


crusher11

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crusher11

I'm watching Breaking Bad, and some of the conversation is super quiet so I turned on subtitles. This obviously requires the video to be transcoded to burn them in, but it also changed the audio from the original DTS to AC3.

 

Why can't it simply transcode the video and mux it with the original audio?

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Happy2Play

Please post the corresponding server and ffmpeg logs.

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Happy2Play

But how does that tie in to this specific context?

 

The delivery method changed when you add I assume unsupported subtitles and that method required the audio track to be changes also.

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Because the original delivery method is a completed static file. When you have to convert on the fly that's no longer the case. I assume you don't want to wait for the entire file to be converted, so we use a streaming protocol that allows us to send small chunks at a time.

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Happy2Play

But I'm still not seeing why the remux can't use the original delivery method.

 

You have not provided the ffmpeg log so we don't know exactly what is going on.  But the file is not being remuxed anymore it is being converted/transcoded.

Edited by Happy2Play
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rbjtech

If you want to maintain the original video and DTS audio - then use an external subtitle text file (.srt) - then it would most likely not need to transcode in the first place...

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Happy2Play

That is where I was headed but did not know the specifics of this transcode session.

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crusher11

It's PGS from the BDs. I'm aware that requires the video to be transcoded, I just didn't understand why it would affect the audio.

 

Because the original delivery method is a completed static file. When you have to convert on the fly that's no longer the case. I assume you don't want to wait for the entire file to be converted, so we use a streaming protocol that allows us to send small chunks at a time.

This is the sort of explanation I was looking for, thanks.

Edited by crusher11
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