[FFmpeg-devel] [PATCH] When PMT is found, we have found mpegts header information

[Baptiste Coudurier]

On 04/19/2010 05:07 AM, Joakim Plate wrote:
> Baptiste Coudurier<baptiste.coudurier<at>  gmail.com>  writes:
>
>>>
>>> My patch only changes what happens during probesize, where it makes
>>> av_find_stream_info stop after first pmt is found. It does not stop the
>>> demuxer from adding more streams later (even as the doxy above would
>>> suggest that is against api), so further stream will still be found.
>>
>> Technically by not setting AVFMT_NOHEADER it will make it stop after all
>> streams
>> detected in the first PMT have parameters information.
>>
>> Breaking API is certainly not wanted.
>> However I think API could be extended to allow this usage. This could be
>> done that makes av_find_stream_info ignore AVFMT_NO_HEADER.
>> Would that work for you ?
>
> Not sure if you intended to attach a patch, but yea if av_find_stream_info
> ignored AVFMT_NO_HEADER after first PMT was found that would work just fine.
>
> The point is just to avoid searching the full probesize. For low bitrate live
> stream that can take some time.
>
> I can't see a good solution to how to do above thou. One can for example not
> just stop av_find_stream_info as soon as it has found one stream. Standard mpeg
> demuxer has no similar mid stream header that shows up that contains the
> complete list of streams in the file after that point (maybe it has, but it's
> not used anyway).
>
> One would have to extend the demuxer/utils.c interface with some additional
> flag, and i'm not sure it's really worth it, given the one use case of
> AVFMT_NO_HEADER.

It's not one use case like I explained to you, it's part of the API.
I don't think breaking is an option unless other people are ok with it.

Michael ?

-- 
Baptiste COUDURIER
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                                  http://www.ffmpeg.org