[FFmpeg-soc] [PATCH] xiph packetizer

[Josh Allmann]

On 29 July 2010 04:54, Martin Storsjö <martin at martin.st> wrote:
> On Thu, 29 Jul 2010, Josh Allmann wrote:
>
>> > Also, there's an issue with vorbis timestamps if you stream copy from an
>> > ogg file - not all packets have pts/dts set when reading them, and for
>> > vorbis, you'd need to decode it to figure out the proper length of each
>> > frame. In ffmpeg.c, lines 1622-1623, the pts is updated using an estimate
>> > of the frame size, which doesn't turn out to be right (in my case at
>> > least).
>> >
>> > If playing only vorbis over RTSP/RTP, it still worked, but the timestamps
>> > advanced slowly from 0 to perhaps 1, then jumped to 5-6 seconds, advanced
>> > slowly there again, and jumped onwards when the ogg demuxer returned a
>> > packet that actually had a timestamp. Combined with a video stream, it
>> > doesn't work too well in that setup of course.
>> >
>> > If live transcoding into theora/vorbis, and sending it out over RTSP/RTP,
>> > it seemed to work really well, though!
>> >
>>
>> That's pretty strange, I would like to see your sample. With Big Buck
>> Bunny, Vorbis standalone timestamps are fairly linear.
>
> Can you give an url to this test clip?
>

http://mirrorblender.top-ix.org/peach/bigbuckbunny_movies/big_buck_bunny_480p_stereo.ogg

>> Using Theora and Vorbis together with RTSP/RTP, things work well.
>> Theora standalone is still full of artifacts around motion with TCP,
>> and UDP is a slideshow because of all the dropped packets. Tomorrow,
>> I'll copy over the packetization routine from Feng and see if the
>> results are more sane.
>
> Hmm, that sounds really strange. Can you give the command lines that
> you've used for these test setups?
>

ffmpeg -re -i acodec copy -vcodec copy -f rtsp rtsp://localhost/foo.sdp

also with -an, -vn, and ?tcp variants.

ffplay rtsp://localhost/foo.sdp

Josh