[FFmpeg-devel] [PATCH] ffmpeg_opt: discard packets correctly

Michael Niedermayer michael at niedermayer.cc
Mon Jul 13 13:11:12 CEST 2015

On Mon, Jul 13, 2015 at 02:44:00AM -0400, Ganesh Ajjanagadde wrote:
> libav commit 13f6917c merged in 574dcb5b results in
> unnecessary seeks due to discarded packets;
> especially problematic over a network.
> Fixes Ticket4126
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ---
>  ffmpeg_opt.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)

i dont think that not marking streams for discarding can be correct
to fix a speed regression.

Reading should not become significantly slower in a
real world (non constructed) case when a stream is marked as discard

See short_seek_threshold, maybe it can be adjusted for http or
network protocols or maybe ff_configure_buffers_for_index() could
adjust things to avoid seeks for discarded streams

A fix purely in ffmpeg_opt also has the disadvanatge that it would
not help any other applications which use libavformat with discarded


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored answer#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
And questions about how to use libav* should be sent to the libav-user ML.
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