> On May 30, 2023, at 12:44, Lance Wang <lance.lmw...@gmail.com> wrote:
>
> 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.
Use mp4toannexb for TS segments is a good practice, but not for
fmp4.
No comments on hevc.
> Also we should
> check the size of extradata.
extradata has a AV_INPUT_BUFFER_PADDING_SIZE, so not necessary.
>
>
>
>> 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.
Yes, but it’s not the first time people don’t follow spec.
>
>
>
>>
>>>
>>>
>>>> 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".
_______________________________________________
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".
