[MPlayer-dev-eng] Strange behavior with audio delayed video files

[Reimar Döffinger]

On 21 February 2014 00:19:25 CET, "Ingo Brückl" <ib at wupperonline.de> wrote:
>Reimar Döffinger wrote on Thu, 20 Feb 2014 21:21:49 +0100:
>
>> On Thu, Feb 20, 2014 at 07:29:50PM +0100, Ingo Brückl wrote:
>>> When I use FFmpeg (ffmpeg -i file.mkv -itsoffset 60 -i file.mkv
>-codec copy
>>> -map 0:v -map 1:a sync.mkv) to adjust an audio delay (60 seconds in
>this
>>> example) I'm experiencing a strange behavior with MPlayer playback.
>The audio
>>> firstly starts at the very beginning as if no delay had been set.
>When I jump
>>> back to the beginning, it runs silent until 60 seconds have been
>played, and
>>> every seeking is OK, i.e. the audio is in sync now.
>>>
>>> So, is the first playback with immediate audio a MPlayer bug?
>
>> MPlayer always plays audio right from the start.
>> I guess you could call that a bug, [...]
>
>I would do so, if audio timestamps say that it should play only later.

That is a feature that is rarely used, and in general rarely useful, and in some ways misguided since silence audio packets cost little and for many formats could be easily prepended.
Thus a quite frequent cause of "timestamps say" is broken initial timestamps. Ignoring them allows them to "change their mind", if you just wait you won't even discover that.

>Could that easily be changed?

Depends. I guess you could just start adding empty audio if the A-V sync value is too large. But there are loads of ways it could be done, though probably not that easily.