c++ - H265 编解码器从 hvc1 更改为 hev1

Question

我尝试使用 hevc 视频复制 mp4 文件。源文件有 hvc1 编解码器。

Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668)

复制编解码器后得到 hev1 的值

Stream #0:0(und): Video: hevc (Main) (hev1 / 0x31766568)

我怎样才能得到hvc1？我发现ffmpeg可以用“-tag：v hvc1”（https://stackoverflow.com/questions/32152090/encode-h265-to-hvc1-codec）以及如何在c ++代码中设置标签（FFMpeg复制流没有转码）但它不影响

我的代码：

AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
const char *in_filename, *out_filename;
int ret, i;
int stream_index = 0;
int *stream_mapping = NULL;
int stream_mapping_size = 0;

if (argc < 3) {
    printf("usage: %s input output\n"
        "API example program to remux a media file with libavformat and libavcodec.\n"
        "The output format is guessed according to the file extension.\n"
        "\n", argv[0]);
    return 1;
}

in_filename = argv[1];
out_filename = argv[2];

av_register_all();

if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
    fprintf(stderr, "Could not open input file '%s'", in_filename);
    goto end;
}

if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
    fprintf(stderr, "Failed to retrieve input stream information");
    goto end;
}

av_dump_format(ifmt_ctx, 0, in_filename, 0);

avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
if (!ofmt_ctx) {
    fprintf(stderr, "Could not create output context\n");
    ret = AVERROR_UNKNOWN;
    goto end;
}

stream_mapping_size = ifmt_ctx->nb_streams;
stream_mapping = (int*)av_mallocz_array(stream_mapping_size, sizeof(*stream_mapping));
if (!stream_mapping) {
    ret = AVERROR(ENOMEM);
    goto end;
}

ofmt = ofmt_ctx->oformat;

for (i = 0; i < (int)ifmt_ctx->nb_streams; i++) {
    AVStream *out_stream;
    AVStream *in_stream = ifmt_ctx->streams[i];
    AVCodecParameters *in_codecpar = in_stream->codecpar;
    AVCodec *decoder = avcodec_find_decoder(in_stream->codecpar->codec_id);
    AVCodec *encoder = avcodec_find_encoder(in_stream->codecpar->codec_id);

    if (in_codecpar->codec_type != AVMEDIA_TYPE_AUDIO &&
        in_codecpar->codec_type != AVMEDIA_TYPE_VIDEO &&
        in_codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
        stream_mapping[i] = -1;
        continue;
    }

    stream_mapping[i] = stream_index++;

    out_stream = avformat_new_stream(ofmt_ctx, NULL);
    if (!out_stream) {
        fprintf(stderr, "Failed allocating output stream\n");
        ret = AVERROR_UNKNOWN;
        goto end;
    }

    ret = avcodec_parameters_copy(out_stream->codecpar, in_codecpar);
    if (ret < 0) {
        fprintf(stderr, "Failed to copy codec parameters\n");
        goto end;
    }

    unsigned int tag = 0;
    // for ffmpeg new api 3.x
    AVCodecParameters *parameters = out_stream->codecpar;
    if (av_codec_get_tag2(ofmt_ctx->oformat->codec_tag, encoder->id, &tag) == 0) {
        av_log(NULL, AV_LOG_ERROR, "could not find codec tag for codec id %d, default to 0.\n", encoder->id);
    }
    parameters->codec_tag = tag;
    out_stream->codec = avcodec_alloc_context3(encoder);
    // more setting for stream->codec
    avcodec_parameters_to_context(out_stream->codec, parameters);
}
av_dump_format(ofmt_ctx, 0, out_filename, 1);

if (!(ofmt->flags & AVFMT_NOFILE)) {
    ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
    if (ret < 0) {
        fprintf(stderr, "Could not open output file '%s'", out_filename);
        goto end;
    }
}

ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
    fprintf(stderr, "Error occurred when opening output file\n");
    goto end;
}

while (1) {
    AVStream *in_stream, *out_stream;

    ret = av_read_frame(ifmt_ctx, &pkt);
    if (ret < 0)
        break;

    in_stream = ifmt_ctx->streams[pkt.stream_index];
    if (pkt.stream_index >= stream_mapping_size ||
        stream_mapping[pkt.stream_index] < 0) {
        av_packet_unref(&pkt);
        continue;
    }

    pkt.stream_index = stream_mapping[pkt.stream_index];
    out_stream = ofmt_ctx->streams[pkt.stream_index];
    log_packet(ifmt_ctx, &pkt, "in");

    /* copy packet */
    pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
    pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
    pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
    pkt.pos = -1;
    log_packet(ofmt_ctx, &pkt, "out");

    ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
    if (ret < 0) {
        fprintf(stderr, "Error muxing packet\n");
        break;
    }
    av_packet_unref(&pkt);
}

av_write_trailer(ofmt_ctx);

结尾：

avformat_close_input(&ifmt_ctx);

/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
    avio_closep(&ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);

av_freep(&stream_mapping);

if (ret < 0 && ret != AVERROR_EOF) {
    fprintf(stderr, "Error occurred: %s\n", av_errTOstr(ret).c_str());
    return 1;
}

改动后：

    out_stream = avformat_new_stream(ofmt_ctx, NULL);
    ret = avcodec_parameters_copy(out_stream->codecpar, in_codecpar);

    AVCodecParameters *parameters = out_stream->codecpar;
    unsigned int tag = 0;
    av_codec_get_tag2(ofmt_ctx->oformat->codec_tag, encoder->id, &tag) == 0);
    parameters->codec_tag = tag;

    out_stream->codec = avcodec_alloc_context3(encoder);
    avcodec_parameters_to_context(out_stream->codec, parameters);

    if (in_codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
        parameters->codec_tag = MKTAG('h', 'v', 'c', '1');
    }
}

av_dump_format(ofmt_ctx, 0, out_filename, 1);
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);

ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
    fprintf(stderr, "Error write header: %s\n", av_errTOstr(ret). c_str());
    goto end;
}

标签： c++ffmpeglibavcodec