[Ffmpeg-devel] Dealing with packet loss

Patrick Noffke patrickn
Fri Oct 21 02:51:09 CEST 2005

> If you stay with ffmpeg's mpeg4, I think you should try
> - a smaller GOP size (-g), maybe something around ten?

I'm trying to keep a fairly low bandwidth consumption.  Increasing the frequency of the I frames (if that's the right term for MPEG-4) tends to result in a higher bit rate.  Also, an ethereal capture from streaming over the internet indicates most of the packets are getting lost from the I frames.

> - data partitioning (option "vdpart" in mencoder, "-part" in ffmpeg)

The idea of data partitioning sounds interesting, and an RFC draft (http://www.ietf.cnri.reston.va.us/internet-drafts/draft-ietf-avt-ulp-11.txt) on FEC for RTP suggests uneven FEC would be suitable for data partitioned like this (basically the more important bits get more FEC protection).  But I'm not aware of RFCs or standards for streaming partitioned data.  

Use of -part with ffmpeg creates two files, though I don't understand their relationship.  Mplayer wasn't able to play the larger of the two files created by ffmpeg, and I didn't see anything in the mplayer man page for playback of partitioned MPEG-4.

Is there an MPEG-4 expert out there that knows the "correct" way of packaging, streaming, and demultiplexing partitioned data?  And how can this improve error resilience, do I need to then use something like the uneven FEC method?


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