[FFmpeg-devel] FLV playback/seeking over HTTP

Michael Niedermayer michaelni
Sat Mar 8 01:17:55 CET 2008


On Tue, Mar 04, 2008 at 02:35:12PM -0800, Jason Barrett Prado wrote:
> [cross-posted to libav-user and ffmpeg-devel because this is both for an app
> and will hopefully result in a patch]
> As part of an app I am including the ability to play FLVs sent over HTTP,
> and I am trying to implement seeking through them in a nice way. I notice
> that when the Flash player for YouTube seeks, it makes one HTTP request to
> start at a calculated byte offset, and then it just goes. When I
> call av_seek_frame in my libav-using app, many requests seem to be made as
> the byte offset jumps about 150k at a time until it finds the right spot,
> then play resumes. This happens both on YouTube-esque servers (I have
> patched http.c to deal with their broken HTTP range requests) and on servers
> that support the HTTP Range: header.
> Is it the case that the Flash FLV player is capable of seeking directly to
> byte offsets of keyframes, while ffmpeg's FLV code is not? Has anyone looked
> into this issue, and how incredibly difficult would it be to implement
> better seeking?

Flvs can have an index, neither our muxer nor demuxer supports such index
There was a very broken patch posted which added muxing support.
A clean and correct patch is welcome and should not be very difficult to

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored awnser#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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