[libav-api] Remuxing H264 stream from RTSP to mp4.

[Roman Savchenko]

Hi,

I trying to remux H264 rtsp based stream to mp4 file on disk and I have
problem. Its converted without any warnings or errors but stream doesn't
displayed in player(for example vlc).

My code:

//open part

int errnum = 0;

AVOutputFormat *av_out_fmt = av_guess_format(nullptr, dst.c_str(), nullptr);
if (!av_out_fmt)
{
    throw std::runtime_error("Can't guess format by passed dest: " + dst);
}

av_out_fmt_ctx = avformat_alloc_context();
av_out_fmt_ctx->oformat = av_out_fmt;

if (!av_out_fmt_ctx)
{
    throw std::runtime_error("Could not create output context");
}

for (uint32_t i = 0; i < av_in_fmt_ctx->nb_streams; ++i)
{
    if (av_in_fmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
    {
        AVStream *in_stream = av_in_fmt_ctx->streams[i];
        AVStream *out_stream = avformat_new_stream(av_out_fmt_ctx,
in_stream->codec->codec);

        if (!out_stream)
        {
            throw std::runtime_error("Failed allocating output stream");
        }

        if ((errnum = avcodec_copy_context(out_stream->codec,
in_stream->codec)) < 0)
        {
            throw std::runtime_error("Failed to copy context from
input to output stream codec context. Error: " +
AVHelper::error_to_string(errnum));
        }

        out_stream->time_base           = in_stream->time_base;
        out_stream->codec->codec_id     = in_stream->codec->codec_id;
        out_stream->sample_aspect_ratio = in_stream->sample_aspect_ratio;

        if (av_out_fmt->flags & AVFMT_GLOBALHEADER)
        {
            out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
        }
    }
}

if (!(av_out_fmt->flags & AVFMT_NOFILE))
{
    if (avio_open(&av_out_fmt_ctx->pb, dst.c_str(), AVIO_FLAG_WRITE) < 0)
    {
        throw std::runtime_error("Could not open output: " + dst);
    }
}

avformat_write_header(av_out_fmt_ctx, nullptr);


//write part

int av_stream_idx = av_in_pkt->stream_index;

const AVCodecContext *in_codec_ctx  =
pimpl->av_in_fmt_ctx->streams[av_stream_idx]->codec;
const AVCodecContext *out_codec_ctx =
pimpl->av_out_fmt_ctx->streams[av_stream_idx]->codec;

assert(in_codec_ctx->codec_id == out_codec_ctx->codec_id);

AVPacket av_out_pkt;
av_init_packet(&av_out_pkt);

AVStream *in_stream  = pimpl->av_in_fmt_ctx->streams[av_stream_idx];
AVStream *out_stream = pimpl->av_out_fmt_ctx->streams[av_stream_idx];

av_out_pkt.stream_index = av_in_pkt->stream_index;

av_out_pkt.size = av_in_pkt->size;
av_out_pkt.data = av_in_pkt->data;

av_out_pkt.pts = av_in_pkt->pts  == int64_t(AV_NOPTS_VALUE) ? AV_NOPTS_VALUE
    : av_rescale_q_rnd(av_in_pkt->pts, in_stream->time_base,
out_stream->time_base, AV_ROUND_NEAR_INF);
av_out_pkt.dts = av_rescale_q_rnd(av_in_pkt->dts,
in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF);

av_out_pkt.duration = av_rescale_q(av_in_pkt->duration,
in_stream->time_base, out_stream->time_base);
av_out_pkt.pos = -1;

int ret = av_interleaved_write_frame(pimpl->av_out_fmt_ctx, av_out_pkt);


//close part

if (av_out_fmt_ctx)
{
    if (!av_out_fmt_ctx->pb->error)
    {
        av_write_trailer(av_out_fmt_ctx);
    }

    if ((av_out_fmt_ctx->pb && !(av_out_fmt_ctx->oformat->flags &
AVFMT_NOFILE)))
    {
        avio_closep(&av_out_fmt_ctx->pb);
    }

    avformat_free_context(av_out_fmt_ctx);
}


Can someone help me with that?


p.s. If i chage mp4 to flv all is ok.
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