[FFmpeg-devel] [PATCH] AVPacket.display_duration

Baptiste Coudurier baptiste.coudurier
Tue Sep 9 04:21:09 CEST 2008

Hi guys,

Michael Niedermayer wrote:
> On Tue, Sep 09, 2008 at 01:56:29AM +0200, Aurelien Jacobs wrote:
>> Michael Niedermayer wrote:
>>> On Fri, Sep 05, 2008 at 05:35:13PM +0200, Aurelien Jacobs wrote:
>>>> Hi,
>>>> For some subtitles track, each AVPacket must carry the display duration
>>>> of the contained subtitle.
>>>> The attached patch adds a dedicated AVPacket.display_duration field.
>>> Iam not against this, but i would like to understand better for which cases
>>> it is needed.
>>> plain UTF-8 and ASCII ?
>> Exactly.
>>> If so does mov, avi, asf, ... support plain UTF-8 and ASCII ?
>> I don't think so...
>>> if yes how do they know the display_duration ?
>> The fact that they can't store any display duration just prevent
>> them from storing plain text subtitles. At least I think so.
>> Another possibility would be to not support any kind of plain text
>> subtitles at all in ffmpeg. Demuxers could convert them to SRT,
>> which is basically plain text + timing information. But I'm still
>> not sure if I really like this solution.
> iam fine with adding display_duration to AVPacket, the only minor
> dislike i have with this solution is that codecs with very small
> packets might see a minor speedloss with added fields. But then
> not adding needed fields is no solution, some other solution for
> these small packet audio codecs has to be found if it turns out that
> the AVPacket handling overhead matters.
> So again iam ok with adding display_duration.

So Matroska packets will have 3 kinds of duration ? normal, convergence,
and display ? Or is display supposed to replace convergence ? Or am I
missing something ?

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
Smartjog USA Inc.                                http://www.smartjog.com
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