Jan,
Yes, that's the one, the latest draft I believe. The descriptor byte is the bare minimum required for VP9, which could optionally be followed by one or two byte serial picture ID (used by receiver to identify problematic frames in its RTCP feedback to the sender), and some more opaque scalability structure information (which could store frame resolution among other things). The optional parts don't seem to affect my use case (I added the gstreamer take on it at some point but didn't see any changes for better or worth),
Thanks Alex On 6/1/19 2:14 PM, Jan Ekström wrote:
Hi, On Sat, Jun 1, 2019 at 8:35 PM Alex Protasenko <aprotase...@bkmks.com> wrote:Hello, I'm trying to play some realtime video sources (web/IP cam) using WebRTC in a browser. I'm sending RTP stream via Janus gateway using VP9 codec, hardware transcoded using ffmpeg. Everything works fine except random frame corruption happening around moving objects, portions of frame "flowing off the screen" and such until next keyframe fixes it. This happens consistently especially at higher framerates. It turns out the issue could be narrowed down to the VP9 RTP packetizer. The problem is it's not marking P frames vs I frames in the VP9 payload descriptor octet (the P bit). Gstreamer does that and doesn't experience any such corruption issues. I added this simple change and now WebRTC plays any stream 100% solid and corruption free for me. Could somebody implement this simple fix in the upstream. Basically in libavformat/rtpenc_vp9.c add something to the effect of the following two lines (to set the P bit for all but I frames): /* mark the first fragment */ *rtp_ctx->buf_ptr++ = 0x08; + if (!keyframe) { + rtp_ctx->buf[0] |= 0x40; Where the "keyframe" is an additional boolean parameter to the ff_rtp_send_vp9 function which could be called as: ff_rtp_send_vp9(s1, pkt->data, size, pkt->flags & AV_PKT_FLAG_KEY);Is https://tools.ietf.org/html/draft-ietf-payload-vp9-06#page-7 the correct specification for VP9 in RTP? Best regards, Jan _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
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