[Libav-user] avio_alloc_context and write_packet callback

[Denis Gottardello]

Hi, I'm using mux.c example to write a file called a.mp4.
In order to do this I need to use the write_packet callback.
So, in the mux.c example file, after the line 566 I have added these lines of codes:

*566*
    /* allocate the output media context */
    avformat_alloc_output_context2(&oc, NULL, NULL, filename);
    if (!oc) {
        printf("Could not deduce output format from file extension: using MPEG.\n");
        avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
    }
    if (!oc)
        return 1;

*// my code*
pBuffer= (uint8_t*)av_malloc(BUFFERSIZE);
pAVIOContext= avio_alloc_context(pBuffer, BUFFERSIZE, 1, this, nullptr, *write_packet*, nullptr);

*// my code*
*oc->pb= pAVIOContext;*

After that I have removed the lines

*599*
    /* open the output file, if needed */
    if (!(fmt->flags & AVFMT_NOFILE)) {
        ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
        if (ret < 0) {
            fprintf(stderr, "Could not open '%s': %s\n", filename,
                    av_err2str(ret));
            return 1;
        }
    }

Now my callback is called but the file produced is different from the one produced by avio_open() (without using the callback).
Is my approach correct or have I to use another way in order to use write_packet callback?


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--------
[1] http://www.labcsp.com
[2] http://www.denisgottardello.it
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