On Tue, May 30, 2023 at 11:09 AM "zhilizhao(赵志立)" <quinkbl...@foxmail.com>
wrote:
>
>
> > On May 30, 2023, at 09:03, Lance Wang <lance.lmw...@gmail.com> wrote:
> >
> > On Mon, May 29, 2023 at 10:16 PM Zhao Zhili <quinkbl...@foxmail.com>
> wrote:
> >
> >> From: Zhao Zhili <zhiliz...@tencent.com>
> >>
> >> Signed-off-by: Zhao Zhili <zhiliz...@tencent.com>
> >> ---
> >> libavformat/hlsenc.c | 14 ++++++++++++--
> >> 1 file changed, 12 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> >> index 871afb571b..1e0848ce3d 100644
> >> --- a/libavformat/hlsenc.c
> >> +++ b/libavformat/hlsenc.c
> >> @@ -355,9 +355,19 @@ static void write_codec_attr(AVStream *st,
> >> VariantStream *vs)
> >>
> >> if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
> >> uint8_t *data = st->codecpar->extradata;
> >> - if (data && (data[0] | data[1] | data[2]) == 0 && data[3] == 1
> &&
> >> (data[4] & 0x1F) == 7) {
> >> + if (data) {
> >> + const uint8_t *p;
> >> +
> >> + if (AV_RB32(data) == 0x01 && (data[4] & 0x1F) == 7)
> >> + p = &data[5];
> >> + else if (AV_RB24(data) == 0x01 && (data[3] & 0x1F) == 7)
> >> + p = &data[4];
> >> + else if (data[0] == 0x01) /* avcC */
> >> + p = &data[1];
> >> + else
> >> + goto fail;
> >>
> >
> > how to reproduce the issue? I recall mpegts is annex b format and sps/pps
> > start code is 4 byte always.
>
> For example:
>
> ffmpeg -i foo.mp4 -c copy -hls_playlist_type vod -master_pl_name bar.m3u8
> test.m3u8
>
> 1. The input of hls muxer can be avcc
>
> 2. The output of hls muxer can be avcc too, with fmp4 segments.
>
>
Yes, this is the case. I had to add mp4toannexb bsf after the copy for avcc
input. If we
don't add the format conversion, hevc may have the same issue I guess.
Also we should
check the size of extradata.
> 3. Start code of SPS/PPS should be 0 0 0 1, however, 0 0 1 exist in wild.
> ff_isom_write_avcc() does the same:
>
> /* check for H.264 start code */
> if (AV_RB32(data) != 0x00000001 &&
> AV_RB24(data) != 0x000001) {
> avio_write(pb, data, len);
> return 0;
> }
>
> ff_isom_write_avcc() can be used here, and get/create CODECS attribute can
> be
> shared by multiple muxers. I won't go that further by now.
>
>
The next NALU checking is for SPS only, so one more byte is zero_byte. It's
required by specs:
zero_byte is a single byte equal to 0x00.
When any of the following conditions are true, the zero_byte syntax element
shall be present:
-
– the nal_unit_type within the nal_unit( ) is equal to 7 (sequence
parameter set) or 8 (picture parameter set),
-
– the byte stream NAL unit syntax structure contains the first NAL unit
of an access unit in decoding order, as specified in clause 7.4.1.2.3.
>
> >
> >
> >> snprintf(attr, sizeof(attr),
> >> - "avc1.%02x%02x%02x", data[5], data[6], data[7]);
> >> + "avc1.%02x%02x%02x", p[0], p[1], p[2]);
> >> } else {
> >> goto fail;
> >> }
> >> --
> >> 2.25.1
> >>
> >> _______________________________________________
> >> 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".
> >>
> > _______________________________________________
> > 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".
>
> _______________________________________________
> 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".
>
_______________________________________________
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".
