[FFmpeg-devel] [PATCH] avformat/hlsenc: support CODECS Attribute in hevc EXT-X-STREAM-INF

[Steven Liu]

> 2020年10月12日 下午11:43，Guangxin Xu <oddstone at gmail.com> 写道：
> 
> On Mon, Oct 12, 2020 at 9:57 PM Steven Liu <lq at chinaffmpeg.org> wrote:
> 
>> 
>> 
>>> 在 2020年10月12日，21:45，Guangxin Xu <oddstone at gmail.com> 写道：
>>> 
>>> 
>>> 
>>> On Mon, Oct 12, 2020 at 5:18 PM Steven Liu <lq at chinaffmpeg.org> wrote:
>>> fix ticket: 8904
>>> parse the SPS from extradata and get profile_tier_level
>>> write the profile_tier_level info into CODECS Attribute
>>> 
>>> reference to :
>> https://developer.apple.com/documentation/http_live_streaming/hls_authoring_specification_for_apple_devices/hls_authoring_specification_for_apple_devices_appendixes
>>> 
>>> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
>>> ---
>>> libavformat/hlsenc.c | 41 +++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 41 insertions(+)
>>> 
>>> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
>>> index cb31d6aed7..574d9f81e9 100644
>>> --- a/libavformat/hlsenc.c
>>> +++ b/libavformat/hlsenc.c
>>> @@ -337,6 +337,43 @@ static void write_codec_attr(AVStream *st,
>> VariantStream *vs)
>>>         } else {
>>>             goto fail;
>>>         }
>>> +    } else if (st->codecpar->codec_id == AV_CODEC_ID_HEVC) {
>>> +        uint8_t *data = st->codecpar->extradata;
>>> +        int i = 0;
>>> +        int profile = FF_PROFILE_UNKNOWN;
>>> +        int level = FF_LEVEL_UNKNOWN;
>>> +
>>> +        if (st->codecpar->profile != FF_PROFILE_UNKNOWN)
>>> +            profile = st->codecpar->profile;
>>> +        if (st->codecpar->level != FF_LEVEL_UNKNOWN)
>>> +            level = st->codecpar->level;
>>> +
>>> +        while (data && (data - st->codecpar->extradata) <
>> st->codecpar->extradata_size) {
>>> +            /* get HEVC SPS NAL and seek to profile_tier_level */
>>> +            if (data && (data[0] | data[1] | data[2]) == 0 && data[3]
>> == 1 && ((data[4] & 0x42) == 0x42)) {
>>> Read beyond the boundary if data + 1 - st->codecpar->extradata  >=
>> st->codecpar->extradata_size
>> ok
>>> Is it possible reuese ff_hevc_decode_extradata here?
>> it is in libavcodec, i don’t think depend libavcodec in hlsenc is a good
>> way, so parse sps here.
>> 
> Then, we have a lot of hard work:
> 1. remove emulation prevent code.
> 2. get profile/level from vps too.
Do you mean it must or always show in VPS?
I think it should alway in SPS if I’m not misunderstand.
> full details you can check at
> https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/hevc.c#L713
I just want get profile, tier and level in hlsenc,
At first I parse the nalunit as the libavformat/hevc, but I think hlsenc maybe not
need alloc new memory to save the new extract_rbsp, just get the value is ok here.
So I think just check the boundary is ok here, isn’t it?
> 
> thanks
> 
> 
> 
>>> 
>>> +                int rbsp_byte_size;
>>> +                data += 7;
>>> +                /* process by reference General NAL unit syntax */
>>> +                profile = *data & 0x1f;
>>> +                rbsp_byte_size = st->codecpar->extradata_size - (data -
>> st->codecpar->extradata);
>>> +                for (i = 0; i < rbsp_byte_size; i++, data++) {
>>> +                    if (data[0] == 0 && data[1] == 0 && data[2] == 3) {
>>> +                        data += 2;
>>> +                        i++;
>>> +                    }
>>> +                    /* skip 8 + 32 + 4 + 43 + 1 bit */
>>> +                    if (i == 11)
>>> +                        level = *data;
>>> +                }
>>> +                break;
>>> +            }
>>> +            data++;
>>> +        }
>>> +        if (st->codecpar->codec_tag == MKTAG('h','v','c','1') &&
>>> +            profile != FF_PROFILE_UNKNOWN &&
>>> +            level != FF_LEVEL_UNKNOWN) {
>>> +            snprintf(attr, sizeof(attr), "%s.%d.4.L%d.B01",
>> av_fourcc2str(st->codecpar->codec_tag), profile, level);
>>> +        }
>>>     } else if (st->codecpar->codec_id == AV_CODEC_ID_MP2) {
>>>         snprintf(attr, sizeof(attr), "mp4a.40.33");
>>>     } else if (st->codecpar->codec_id == AV_CODEC_ID_MP3) {
>>> @@ -2247,6 +2284,10 @@ static int hls_write_header(AVFormatContext *s)
>>>                 continue;
>>>             }
>>>             avpriv_set_pts_info(outer_st, inner_st->pts_wrap_bits,
>> inner_st->time_base.num, inner_st->time_base.den);
>>> +            if (outer_st->codecpar->codec_id == AV_CODEC_ID_HEVC &&
>>> +                outer_st->codecpar->codec_tag !=
>> MKTAG('h','v','c','1')) {
>>> +                av_log(s, AV_LOG_WARNING, "Stream HEVC is not hvc1, you
>> should use tag:v hvc1 to set it.\n");
>>> +            }
>>>             write_codec_attr(outer_st, vs);
>>> 
>>>         }
>>> --
>>> 2.25.0
>>> 
>>> 
>>> 
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>> 
>> Thanks
>> Steven
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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Thanks

Steven Liu