1837228 - Vendor in ffmpeg's vp9 superframe re-assembly bitstream filter

Status: NEW

(Core :: WebRTC: Audio/Video, task, P3)

Description

[Andreas Pehrson [:pehrsons]]

From bug 1832276 comment 11 it seems likely some decoders will need to be served assembled superframes rather than split ones to work properly. This bug is for vendoring in the assembling bitstream filter from ffmpeg to investigate whether it helps the ffmpeg, ffvpx and AppleVT decoders to decode webrtc svc streams properly.

Comment 1

[Paul Adenot (:padenot)]

Attachment: Bug 1837228 - Vendor in ffmpeg's vp9 superframe re-assembly bitstream filter. r?pehrsons

Comment 2

[Paul Adenot (:padenot)]

Attachment: Bug 1837228 - Expose the BSF API from FFmpeg. r?pehrsons,alwu

Depends on D180332

Comment 3

[Paul Adenot (:padenot)]

API doc is here: https://ffmpeg.org/doxygen/6.0/group__lavc__bsf.html. It looks like it should be:

AVBitStreamFilter * bsf = av_bsf_get_by_name(name_of_the_bsf);
// check null
int rv = av_bsf_alloc(bsf, &bsfCtx);
// check OK
rv = av_bsf_init(bsfCtx);
// check OK
AVPacket pkt;
pkr.data = const_cast<uint8_t*>(the_packet_bytes);
pkt.size = the_packet_size;
do {
  rv = av_bsf_send_packet (bsfCtx, &pkt);
} while (rv == 0); // check error code for reassembly

do {
  rv = av_bsf_receive_packet (bsfCtx, &pkt);
} while (rv == 0); // check error code for receiving assembled packet

// pkt is usable now, merged 

it would make sense do to multiple send calls and a single receive call, since this is assembly of packets. Likely the opposite for superframe split.

I exposed the methods much in the same way we use the FFT from FFmpeg, see the patches for the names I picked, but an example usage of the FFT: https://searchfox.org/mozilla-central/rev/887d4b5da89a11920ed0fd96b7b7f066927a67db/dom/media/webaudio/FFTBlock.h#47

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The following patch is waiting for review from an inactive reviewer:

ID	Title	Author	Reviewer Status
D180332	Bug 1837228 - Vendor in ffmpeg's vp9 superframe re-assembly bitstream filter. r?pehrsons	padenot	pehrsons: Back Aug 1, 2023

:padenot, could you please find another reviewer?

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Comment 5

[Paul Adenot (:padenot)]

Apparently we don't need this, clearing NI.