[FFmpeg-devel] [PATCH v3 0/7] Merge lazy filter initialization in ffmpeg CLI

[Hendrik Leppkes]

On Fri, Mar 3, 2017 at 2:21 PM, Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> the patches break this:
> ./ffmpeg -itsoffset 2 -re -i ~/videos/matrixbench_mpeg2.mpg -vcodec h263 -s cif -an  -t 3 -f rtp rtp://127.0.0.1:19955 >h263.sdp </dev/null & sleep 1 ; ./ffmpeg -protocol_whitelist file,rtp,udp -i h263.sdp -y  -t 0.9 out-h263.avi
>
> It appears that h263.sdp is written later than previously
> and the sdp is needed at the receiving side so this might
> impact some real users
>
> the example above works with a sleep 2 instead of sleep 1
>

This sounds to me like this always was a race condition and could
always fail. There have never been any guarantees on timing, and it
depends on how long probing of the file takes, setup of the filters,
etc.
One of the key changes in this set is that output files are indeed
generated later, once all final format information is fully available,
instead of just guessing and creating the output before the input is
initialized fully, which was just a weird dataflow to begin with.

- Hendrik