Bug 292858
| Summary: | Wrong WebRTC H264 video clock rate since Safari 18.4.1 | ||
|---|---|---|---|
| Product: | WebKit | Reporter: | mgookov |
| Component: | WebRTC | Assignee: | Nobody <webkit-unassigned> |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | Normal | CC: | glendonwalkerii, youennf |
| Priority: | P2 | ||
| Version: | Safari 18 | ||
| Hardware: | iPhone / iPad | ||
| OS: | iOS 18 | ||
mgookov
When I publish video from my iPhone (Safari 18.4.1) (or macOS) via a WebRTC (RTP), the server receives a packet with a timestamp frequency(clock rate) of 900 kHz instead of 90 kHz.
SDP example
a=mid:1
a=rtpmap:96 H264/90000
a=fmtp:96 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640c1f
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtcp-fb:96 goog-remb
a=rtpmap:98 H264/90000
a=fmtp:98 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f
a=rtcp-fb:98 ccm fir
a=rtcp-fb:98 nack
a=rtcp-fb:98 nack pli
a=rtcp-fb:98 goog-remb
a=rtpmap:100 H264/90000
a=fmtp:100 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=640c1f
a=rtcp-fb:100 ccm fir
a=rtcp-fb:100 nack
a=rtcp-fb:100 nack pli
a=rtcp-fb:100 goog-remb
a=rtpmap:102 H264/90000
a=fmtp:102 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42e01f
a=rtcp-fb:102 ccm fir
a=rtcp-fb:102 nack
a=rtcp-fb:102 nack pli
a=rtcp-fb:102 goog-remb
Example of received packets (H264, 30 fps):
sn=1157, timestamp=4133632481
sn=1158, timestamp=4133632481
sn=1159, timestamp=4133632481
sn=1160, timestamp=4133632481
sn=1161, timestamp=4133632481
sn=1162, timestamp=4133665095
sn=1163, timestamp=4133665095
sn=1164, timestamp=4133665095
sn=1165, timestamp=4133665095
sn=1166, timestamp=4133665095
sn=1167, timestamp=4133699279
sn=1168, timestamp=4133699279
sn=1169, timestamp=4133699279
sn=1170, timestamp=4133699279
sn=1171, timestamp=4133699279
sn=1172, timestamp=4133731294
sn=1173, timestamp=4133731294
sn=1174, timestamp=4133731294
sn=1175, timestamp=4133731294
sn=1176, timestamp=4133731294
The diff between frame timestamps is about 32000. The same for SenderReport.
If I use clock rate = 900 kHz, audio/video synchronization is good, with 90 kHz it doesn't work.
| Attachments | ||
|---|---|---|
| Add attachment proposed patch, testcase, etc. |
youenn fablet
This is likely https://bugs.webkit.org/show_bug.cgi?id=292273.
youenn fablet
*** This bug has been marked as a duplicate of bug 292273 ***