[Libav-user] avio raw yuv

Anshul anshul.ffmpeg at gmail.com
Fri Sep 12 01:33:02 CEST 2014

On September 12, 2014 4:22:27 AM IST, Anthony Clark <clarka193 at potsdam.edu> wrote:
>> On September 12, 2014 2:46:49 AM IST, Anthony Clark
>> <clarka193 at potsdam.edu> wrote:
>>>Hey all,
>>>I have a YUV file I created with something like `ffmpeg -i video.mp4
>>>rawvideo -pix_fmt yuv420p out.yuv`. I want to use libav* to retrieve
>>>frames from this raw file. Any clues? So far I just create an
>>>`av_file_map` and get the data that way - it's a little primitive.
>>>YUV have a demuxer? Decoder? I couldn't find anything in 2.2.4's
>>>but maybe I looked at the wrong things.
>>>Oh, I should note that using the `avio_reading.c` example in 2.2.x
>>>on `avformat_open_input` - telling me YUV/raw is a little special.
>>>help is greatly appreciated!
>>>Libav-user mailing list
>>>Libav-user at ffmpeg.org
>> You need to specify size through avoptions
>I think I know what you mean. So, I made these modification to
>`avio_reading.c` ...
>105:AVInputFormat * input = av_find_input_format("rawvideo");
>    AVDictionary * opts;
>    av_dict_set(&opts, "video_size", "352x288", 0);
>    ret = avformat_open_input(&fmt_ctx, NULL, input, &opts);
>    if (ret < 0) {
>        fprintf(stderr, "Could not open input\n");
>        goto end;
>It no longer fails via avformat_open_input. BUT, the file mapping is
>and I only get 2 really large (as large as my file) sized buffers. 

I think you should try looking deeper here, why does it fail, what makes decoder give u whole file.
May be using gdb u can find out.

>to use various `av_opt_set` routines to set the AVOptions for the
>decoder, but everything looks "private"... maybe I'm missing something.
>Any advice is appreciated. Thanks again for the reply
>> -Anshul
>Libav-user mailing list
>Libav-user at ffmpeg.org

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