Interlaced video decoding with openh264dec

[Nicolas Dufresne]

Le lundi 20 décembre 2021 à 14:07 +0530, Aniket Hande via gstreamer-devel a
écrit :
> Hi,
> I've been trying to decode an MPEG-2 TS stream using software decoding. The
> stream codec is H.264. I'm using openh264dec to get frames for some other
> purposes. However, I'm unable to get the decoder running. I checked and found
> my source is interlaced and thus getting following in GST logs.
> 
> > 0:00:00.469505066  5691 0x55e3e03ccde0 WARN             openh264dec
> > :0::<openh264dec0> [OpenH264] this = 0x0x55e3e03de000, Warning:ParseSps():
> > frame_mbs_only_flag (0) not supported.
> > 0:00:01.462231994  5691 0x55e3e03ccde0 WARN             openh264dec
> > :0::<openh264dec0> [OpenH264] this = 0x0x55e3e03de000, Warning:ParseSps():
> > frame_mbs_only_flag (0) not supported.
> > 0:00:02.459178726  5691 0x55e3e03ccde0 WARN             openh264dec
> > :0::<openh264dec0> [OpenH264] this = 0x0x55e3e03de000, Warning:ParseSps():
> > frame_mbs_only_flag (0) not supported.
> > 0:00:03.456121210  5691 0x55e3e03ccde0 WARN             openh264dec
> > :0::<openh264dec0> [OpenH264] this = 0x0x55e3e03de000, Warning:ParseSps():
> > frame_mbs_only_flag (0) not supported.
> > 0:00:03.651262186  5691 0x55e3e03ccde0 WARN            videodecoder
> > gstvideodecoder.c:1140:gst_video_decoder_sink_event_default:<openh264dec0>
> > error: No valid frames decoded before end of stream
> > 
> 
> 
> Is there any way I can get openh264dec to decode my interlaced stream or is my
> interpretation wrong here?
> I'm using Gstreamer 1.16.

This decoder is not implementing the case where bitstream parameter
frame_mbs_only_flag == 0. Your streams is using that parameter, there is nothing
we can do in GStreamer. I'd say use a more complete decode, notably ffmpeg one
(avdec_h264).

>