On 26/07/14 00:58, Joseph Rosensweig wrote:
> I've just started to learn about VP8, so give me some slack if this is a
> dumb question.
> H.264 Example
>
> In the past I've worked mostly with H.264. Whenever I needed to parse H.264
> bit streams, I would leverage libav to help me and use something like this
>
> av_register_all();
>
> _ioContext = avio_alloc_context(
> encodedData,
> H264_READER_BUF_SIZE,
> 0,
> 0,
> &readFunction,
> NULL,
> NULL);
> if (_ioContext == NULL)
> throw std::exception("Unable to create AV IO Context");
>
> AVInputFormat *h264Format = av_find_input_format("h264");
> if (h264Format == NULL) {
> throw std::exception("Unable to find H264 Format");
> }
>
> _context = avformat_alloc_context();
> _context->pb = _ioContext;
>
> ret = avformat_open_input(&_context,
> "",
> h264Format,
> NULL);
>
> if (ret != 0) {
> throw std::exception(
> "Failed to open input file :" +
> std::string(_avErrToString(ret)));
> }
>
> ....
>
> ....
>
> int ret = av_read_frame(_context, &_packet);
>
> VP8
>
> The above method has worked great for parsing the H.264 bit streams and
> providing me with H.264 frames to feed to my own decoding infrastructure.
>
> I'm trying to duplicate the same effort with VP8. I tried using this code
> as a basis and instead of looking for the "h264" format, I've tried "vp8"
> and "webm". "vp8" doesn't seem valid, but "webm" is able to load a format.
> However when I get to avformat_open_input I get this error:
h264 is a codec and also an elementary stream format
> [matroska,webm @ 0x101812400] Unknown entry 0xF0
> [matroska,webm @ 0x101812400] EBML header using unsupported features
> (EBML version 0, doctype (null), doc version 0)
> Failed to open input file :Not yet implemented in FFmpeg, patches welcome
>
> Am I out of look? Or am I just approaching this incorrectly?
You may ask libav which is the format you are trying to demux, I think
it could be ivf (that's the closest to a vp8 elementary stream) if you
want to keep restricting what is supported and what is not.
lu
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