<div dir="ltr">But now I see in vlc that the MPEG4 codec is actually named "mp4v" .So that's the name I have to specificy in --enable-decoder when doing FFMPEG config?<div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Nov 9, 2017 at 7:26 PM, Michael IV <span dir="ltr"><<a href="mailto:explomaster@gmail.com" target="_blank">explomaster@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">And testing the actual codecId of the video stream in the file I am also getting NULL for avcodec_find_decoder:<div><br></div><div><div> ret = av_find_best_stream(<wbr>pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);</div><div><span style="white-space:pre-wrap"> </span>st = pFormatCtx->streams[ret];</div><div><span style="white-space:pre-wrap"> </span>AVCodecContext *dec_ctx = NULL;</div><div><span style="white-space:pre-wrap"> </span>AVCodec *dec = NULL;</div><div><span style="white-space:pre-wrap"> </span>dec_ctx = st->codec;</div><div><span style="white-space:pre-wrap"> </span>dec = avcodec_find_decoder(dec_ctx-><wbr>codec_id);</div></div><div><br></div><div> <b> where ec_ctx->codec_id == AV_CODEC_ID_MPEG4</b></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Nov 9, 2017 at 7:22 PM, Michael IV <span dir="ltr"><<a href="mailto:explomaster@gmail.com" target="_blank">explomaster@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="auto">Hi, thanks for the input. Now I am confused even more. All I need is to start demuxing an mp4 file. Those codecs test above is not what I do.</div><div>I started to check those because I am getting into trouble in this part:</div><div><br></div><div><div> pFormatCtx = avformat_alloc_context(); //ok</div><div><span style="white-space:pre-wrap"> </span>AVDictionary *d = NULL; </div><div><span style="white-space:pre-wrap"> </span>av_dict_set(&d, "protocol_whitelist","file", 0); //ok<br></div><div> int ret = avformat_open_input(&pFormatCt<wbr>x, in_f_name , NULL, &d); //ok<br></div></div><div> avformat_find_stream_info(pFo<wbr>rmatCtx, NULL) ///also ok</div><div><br></div><div>But once I get to access the codecpar I hit "access violation reading location:</div><div><br></div><div><b>pFormatCtx->streams[i]->codecp<wbr>ar->codec_type==AVMEDIA_TYPE_<wbr>VIDEO</b><br></div><div><br></div><div>Because my <b>codecpar </b>is not initialized. That's what I don't understand here.</div><div><div class="m_1235953485649798123h5"><div><br></div><div><br></div><div><br></div><div dir="auto"><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Nov 9, 2017 8:14 PM, "Carl Eugen Hoyos" <<a href="mailto:ceffmpeg@gmail.com" target="_blank">ceffmpeg@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi!<br>
<br>
> Am 09.11.2017 um 17:13 schrieb Michael IV <<a href="mailto:explomaster@gmail.com" target="_blank">explomaster@gmail.com</a>>:<br>
><br>
> Hi All. What maybe a reason that avcodec_find_decoder returns NULL ?<br>
><br>
> I enabled in my FFMPEG build MOV and h264 demuxer. Configure report clearly<br>
> states that.<br>
><br>
> But doing this test:<br>
><br>
> av_register_all();<br>
> avcodec_register_all();<br>
> avformat_network_init();<br>
> AVCodec* h264codc = avcodec_find_decoder_by_name("<wbr>h264");<br>
<br>
This is supposed to work.<br>
<br>
<br>
> AVCodec* h264codc1 = avcodec_find_decoder_by_name("<wbr>MOV");<br>
<br>
This is not the name of any decoder, mov is a file format, you will find a demuxer (and a muxer) with that name (I think).<br>
<br>
> AVCodec* h264codc3 = avcodec_find_decoder_by_name("<wbr>MPEG4");<br>
<br>
There is codec "mpeg4" but that's not h264.<br>
<br>
> AVCodec* h264codc4 = avcodec_find_decoder_by_name("<wbr>MP4");<br>
<br>
See above for mov, although the same demuxer handles mov and mp4.<br>
<br>
> AVCodec* h264codc5 = avcodec_find_decoder(AV_CODEC_<wbr>ID_MPEG4);<br>
<br>
Again, this codec exists but it's not h264.<br>
<br>
> Only h264codc returns a valid codec.<br>
<br>
<br>
> The only thing I didn't do during build config was not to enable libx264.<br>
<br>
This only means that you have no h264 encoder.<br>
<br>
> May this be the source of the problem? I didn't do that because I just need to demux mp4 movie and get its elementary stream.<br>
<br>
Then you don't care about a decoder, you only need a demuxer (and maybe a parser).<br>
<br>
Carl Eugen<br>
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</blockquote></div></div>
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</blockquote></div><br></div>
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