Hi Konran,
Konran Gerber wrote:
> Hello,
> I'm trying to raw read MPEG2 video using av_read_frame without decoding
> with avcodec_decode_video because I'm doing analysis and therefore I
> have to go quickly through each video file.
>
> Things I need are parameters like repeat_pict, top_field_first,
> interlaced_frame. There is a flag in AVCodecContext parse_only that says
> avcodec_parse_frame can be used to get the frame data. But there is
> neither avcodec_parse_frame in the source code
I suspect this is a residual from some old code, and the comments are
not valid anymore. I believe you do not need to use
avcodec_decode_video(), nor you need an AVCodecContext. In my
understanding, you just need to use the av_read_frame() function
provided by libavformat.
(the documentation says: "Return the next frame of a stream.... For
video, the packet contains exactly one frame....")
[...]
> Any other way to get the frame's raw data? I've tried to evaluate the
> AVPacket content after successfully calling av_read_frame.
IMHO, this should be the right thing to do: call av_read_frame() and
look at pkt.data.
> But here I
> get either the entry point from the first sequence header when I point
> to the beginning of the packet's data member or I get anywhere in the
> buffer's data when I look at packet.data[packet.pos] ... there is no
> valid stream start code at that position.
I think pkt.data (and not pkt.data[pkt.pos]) should contain the frame...
If you already tried looking at it and it does not contain correct data,
then I do not know what to say. Maybe someone else (who knows
libavformat's internals better) will have more information about this.
Anyway, what's the problem you are seeing with pkt.data?
Luca
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