Re: [FFmpeg-devel] [PATCH] libavformat/sdp: VPS is not a mandatory HEVC codec parameter.

From: Koushik Dutta <koushd@gmail.com>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] libavformat/sdp: VPS is not a mandatory HEVC codec parameter.
Date: Tue, 1 Apr 2025 20:33:16 -0700
Message-ID: <CAO4LPj8CxBc7JG5FDHXT2-OWEnPc-tMqxhzhRxUUsg=W9iKarw@mail.gmail.com> (raw)
In-Reply-To: <20250326205057.73627-1-koushd@gmail.com>

Hi, is there any issue with this patch? Here's a sample SDP without
the VPS, that all hikvision cameras send during RTSP DESCRIBE. The VPS
is sent periodically as part of the stream. The sprop-sps and
sprop-pps are lost without this patch because the sprop-vps is not
present.

[rtsp @ 0x12d606fe0] SDP:
v=0
o=- 1743536797185502 1743536797185502 IN IP4 192.168.2.64
s=Media Presentation
e=NONE
b=AS:5100
t=0 0
a=control:rtsp://192.168.2.64:554/ISAPI/Streaming/channels/101/?transportmode=unicast
m=video 0 RTP/AVP 96
c=IN IP4 0.0.0.0
b=AS:5000
a=recvonly
a=x-dimensions:3840,2160
a=control:rtsp://192.168.2.64:554/ISAPI/Streaming/channels/101/trackID=1?transportmode=unicast
a=rtpmap:96 H265/90000
a=fmtp:96 sprop-sps=QgEBAWAAAAMAsAAAAwAAAwCZoAHgIAIcWNrkkUvzcBAQEAg=;
sprop-pps=RAHA8s5wOyQ=
m=audio 0 RTP/AVP 0
c=IN IP4 0.0.0.0
b=AS:50
a=recvonly
a=control:rtsp://192.168.2.64:554/ISAPI/Streaming/channels/101/trackID=2?transportmode=unicast
a=rtpmap:0 PCMU/8000
a=Media_header:MEDIAINFO=494D4B48010200000400050010710110401F000000FA000000000000000000000000000000000000;
a=appversion:1.0

On Wed, Mar 26, 2025 at 1:51 PM <koushd@gmail.com> wrote:
>
> From: Koushik Dutta <koushd@gmail.com>
>
> Many IP cameras do not place VPS in the SDP, and only send it
> in the stream. The RTSP SDP only contains SPS/PPS.
>
> Signed-off-by: Koushik Dutta <koushd@gmail.com>
> ---
>  libavformat/sdp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/sdp.c b/libavformat/sdp.c
> index 28490d77f3..64fe9d61ac 100644
> --- a/libavformat/sdp.c
> +++ b/libavformat/sdp.c
> @@ -301,7 +301,9 @@ static int extradata2psets_hevc(AVFormatContext *fmt, const AVCodecParameters *p
>              pos += len;
>          }
>      }
> -    if (!ps_pos[0] || !ps_pos[1] || !ps_pos[2])
> +
> +    // VPS is not mandatory
> +    if (!ps_pos[1] || !ps_pos[2])
>          goto err;
>
>      psets = av_mallocz(MAX_PSET_SIZE);
> @@ -314,6 +316,8 @@ static int extradata2psets_hevc(AVFormatContext *fmt, const AVCodecParameters *p
>
>      for (i = 0; i < 3; i++) {
>          pos = ps_pos[i];
> +        if (!pos)
> +            continue;
>
>          if (i > 0)
>              av_strlcat(psets, "; ", MAX_PSET_SIZE);
> --
> 2.39.5 (Apple Git-154)
>
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