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• x264 encoded frames into a mp4 container with ffmpeg API

  10 septembre 2019, par PJD

  I'm struggling with understanding what is and what is not needed in getting my already encoded x264 frames into a video container file using ffmpeg's libavformat API.

  



  My current program will get the x264 frames like this -

  



  while( x264_encoder_delayed_frames( h ) )
{
    printf("Writing delayed frame %u\n", delayed_frame_counter++);
    i_frame_size = x264_encoder_encode( h, &nal, &i_nal, NULL, &pic_out );
    if( i_frame_size < 0 ) {
            printf("Failed to encode a delayed x264 frame.\n");
            return ERROR;
        }
    else if( i_frame_size )
    {
        if( !fwrite(nal->p_payload, i_frame_size, 1, video_file_ptr) ) {
            printf("Failed to write a delayed x264 frame.\n");
            return ERROR;
        }
    }
}


  



  If I use the CLI to the ffmpeg binary, I can put these frames into a container using :

  



  ffmpeg -i "raw_frames.h264" -c:v copy -f mp4 "video.mp4"


  



  I would like to code this function into my program using the libavformat API though. I'm a little stuck in the concepts and the order on which each ffmpeg function is needed to be called.

  



  So far I have written :

  



          mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
        printf("Guessed format\n");

        int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
        printf("Created context = %d\n", ret);
        printf("Format = %s\n", mAVFormatContext->oformat->name);

        mAVStream = avformat_new_stream(mAVFormatContext, 0);
        if (!mAVStream) {
            printf("Failed allocating output stream\n");
        } else {
            printf("Allocated stream.\n");
        }

        mAVCodecParameters = mAVStream->codecpar;
        if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
            mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
            mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
            printf("Invalid codec?\n");
        }

        if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
            ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
            if (ret < 0) {
              printf("Could not open output file '%s'", "gen_vid.mp4");
            }
          }

        ret = avformat_write_header(mAVFormatContext, NULL);
        if (ret < 0) {
          printf("Error occurred when opening output file\n");
        }


  



  This will print out :

  



  Guessed format
Created context = 0
Format = mp4
Allocated stream.
Invalid codec?
[mp4 @ 0x55ffcea2a2c0] Could not find tag for codec none in stream #0, codec not currently supported in container
Error occurred when opening output file


  



  How can I make sure the codec type is set correctly for my video ?
Next I need to somehow point my mAVStream to use my x264 frames - advice would be great.

  



  Update 1 :
So I've tried to set the H264 codec, so the codec's meta-data is available. I seem to hit 2 newer issues now.
1) It cannot find the device and therefore cannot configure the encoder.
2) I get the "dimensions not set".

  



  mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
printf("Guessed format\n");

// MUST allocate the media file format context. 
int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
printf("Created context = %d\n", ret);
printf("Format = %s\n", mAVFormatContext->oformat->name);

// Even though we already have encoded the H264 frames using x264,
// we still need the codec's meta-data.
const AVCodec *mAVCodec;
mAVCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!mAVCodec) {
    fprintf(stderr, "Codec '%s' not found\n", "H264");
    exit(1);
}
mAVCodecContext = avcodec_alloc_context3(mAVCodec);
if (!mAVCodecContext) {
    fprintf(stderr, "Could not allocate video codec context\n");
    exit(1);
}
printf("Codec context allocated with defaults.\n");
/* put sample parameters */
mAVCodecContext->bit_rate = 400000;
mAVCodecContext->width = width;
mAVCodecContext->height = height;
mAVCodecContext->time_base = (AVRational){1, 30};
mAVCodecContext->framerate = (AVRational){30, 1};
mAVCodecContext->gop_size = 10;
mAVCodecContext->level = 31;
mAVCodecContext->max_b_frames = 1;
mAVCodecContext->pix_fmt = AV_PIX_FMT_NV12;

av_opt_set(mAVCodecContext->priv_data, "preset", "slow", 0);
printf("Set codec parameters.\n");

// Initialize the AVCodecContext to use the given AVCodec.
avcodec_open2(mAVCodecContext, mAVCodec, NULL);            

// Add a new stream to a media file. Must be called before
// calling avformat_write_header().
mAVStream = avformat_new_stream(mAVFormatContext, mAVCodec);
if (!mAVStream) {
    printf("Failed allocating output stream\n");
} else {
    printf("Allocated stream.\n");
}

// TODO How should codecpar be set?
mAVCodecParameters = mAVStream->codecpar;
if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
    mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
    mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
    printf("Invalid codec?\n");
}

if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
    ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
    if (ret < 0) {
      printf("Could not open output file '%s'", "gen_vid.mp4");
    }
  }
printf("Called avio_open()\n");

// MUST write a header.
ret = avformat_write_header(mAVFormatContext, NULL);
if (ret < 0) {
  printf("Error occurred when opening output file (writing header).\n");
}


  



  Now I am getting this output -

  



  Guessed format
Created context = 0
Format = mp4
Codec context allocated with defaults.
Set codec parameters.
[h264_v4l2m2m @ 0x556460344b40] Could not find a valid device
[h264_v4l2m2m @ 0x556460344b40] can't configure encoder
Allocated stream.
Invalid codec?
Called avio_open()
[mp4 @ 0x5564603442c0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
[mp4 @ 0x5564603442c0] dimensions not set
Error occurred when opening output file (writing header).


  


• x264 encoded frames into a mp4 container with ffmpeg API

  10 septembre 2019, par PJD

  I'm struggling with understanding what is and what is not needed in getting my already encoded x264 frames into a video container file using ffmpeg's libavformat API.

  



  My current program will get the x264 frames like this -

  



  while( x264_encoder_delayed_frames( h ) )
{
    printf("Writing delayed frame %u\n", delayed_frame_counter++);
    i_frame_size = x264_encoder_encode( h, &nal, &i_nal, NULL, &pic_out );
    if( i_frame_size < 0 ) {
            printf("Failed to encode a delayed x264 frame.\n");
            return ERROR;
        }
    else if( i_frame_size )
    {
        if( !fwrite(nal->p_payload, i_frame_size, 1, video_file_ptr) ) {
            printf("Failed to write a delayed x264 frame.\n");
            return ERROR;
        }
    }
}


  



  If I use the CLI to the ffmpeg binary, I can put these frames into a container using :

  



  ffmpeg -i "raw_frames.h264" -c:v copy -f mp4 "video.mp4"


  



  I would like to code this function into my program using the libavformat API though. I'm a little stuck in the concepts and the order on which each ffmpeg function is needed to be called.

  



  So far I have written :

  



          mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
        printf("Guessed format\n");

        int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
        printf("Created context = %d\n", ret);
        printf("Format = %s\n", mAVFormatContext->oformat->name);

        mAVStream = avformat_new_stream(mAVFormatContext, 0);
        if (!mAVStream) {
            printf("Failed allocating output stream\n");
        } else {
            printf("Allocated stream.\n");
        }

        mAVCodecParameters = mAVStream->codecpar;
        if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
            mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
            mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
            printf("Invalid codec?\n");
        }

        if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
            ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
            if (ret < 0) {
              printf("Could not open output file '%s'", "gen_vid.mp4");
            }
          }

        ret = avformat_write_header(mAVFormatContext, NULL);
        if (ret < 0) {
          printf("Error occurred when opening output file\n");
        }


  



  This will print out :

  



  Guessed format
Created context = 0
Format = mp4
Allocated stream.
Invalid codec?
[mp4 @ 0x55ffcea2a2c0] Could not find tag for codec none in stream #0, codec not currently supported in container
Error occurred when opening output file


  



  How can I make sure the codec type is set correctly for my video ?
Next I need to somehow point my mAVStream to use my x264 frames - advice would be great.

  



  Update 1 :
So I've tried to set the H264 codec, so the codec's meta-data is available. I seem to hit 2 newer issues now.
1) It cannot find the device and therefore cannot configure the encoder.
2) I get the "dimensions not set".

  



  mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
printf("Guessed format\n");

// MUST allocate the media file format context. 
int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
printf("Created context = %d\n", ret);
printf("Format = %s\n", mAVFormatContext->oformat->name);

// Even though we already have encoded the H264 frames using x264,
// we still need the codec's meta-data.
const AVCodec *mAVCodec;
mAVCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!mAVCodec) {
    fprintf(stderr, "Codec '%s' not found\n", "H264");
    exit(1);
}
mAVCodecContext = avcodec_alloc_context3(mAVCodec);
if (!mAVCodecContext) {
    fprintf(stderr, "Could not allocate video codec context\n");
    exit(1);
}
printf("Codec context allocated with defaults.\n");
/* put sample parameters */
mAVCodecContext->bit_rate = 400000;
mAVCodecContext->width = width;
mAVCodecContext->height = height;
mAVCodecContext->time_base = (AVRational){1, 30};
mAVCodecContext->framerate = (AVRational){30, 1};
mAVCodecContext->gop_size = 10;
mAVCodecContext->level = 31;
mAVCodecContext->max_b_frames = 1;
mAVCodecContext->pix_fmt = AV_PIX_FMT_NV12;

av_opt_set(mAVCodecContext->priv_data, "preset", "slow", 0);
printf("Set codec parameters.\n");

// Initialize the AVCodecContext to use the given AVCodec.
avcodec_open2(mAVCodecContext, mAVCodec, NULL);            

// Add a new stream to a media file. Must be called before
// calling avformat_write_header().
mAVStream = avformat_new_stream(mAVFormatContext, mAVCodec);
if (!mAVStream) {
    printf("Failed allocating output stream\n");
} else {
    printf("Allocated stream.\n");
}

// TODO How should codecpar be set?
mAVCodecParameters = mAVStream->codecpar;
if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
    mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
    mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
    printf("Invalid codec?\n");
}

if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
    ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
    if (ret < 0) {
      printf("Could not open output file '%s'", "gen_vid.mp4");
    }
  }
printf("Called avio_open()\n");

// MUST write a header.
ret = avformat_write_header(mAVFormatContext, NULL);
if (ret < 0) {
  printf("Error occurred when opening output file (writing header).\n");
}


  



  Now I am getting this output -

  



  Guessed format
Created context = 0
Format = mp4
Codec context allocated with defaults.
Set codec parameters.
[h264_v4l2m2m @ 0x556460344b40] Could not find a valid device
[h264_v4l2m2m @ 0x556460344b40] can't configure encoder
Allocated stream.
Invalid codec?
Called avio_open()
[mp4 @ 0x5564603442c0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
[mp4 @ 0x5564603442c0] dimensions not set
Error occurred when opening output file (writing header).


  


• When converting video through ffmepg show error

  9 septembre 2019, par Krunal

  I am trying to convert video through ffmepg but its show this error
  "Error initializing output stream 1:0 — Error while opening encoder for output stream #1:0 - maybe incorrect parameters such as bit_rate, rate, width or height".
  Its working fine on my system but facing the issue on server.

  Metadata:
  
          major_brand     : qt
  
          minor_version   : 0
  
          compatible_brands: qt
  
          encoder         : Lavf58.20.100
  
          Stream #0:0(eng): Video: h264 (libx264), yuv420p, 426x240, q=-1--1, 400 kb/s, 23.98 fps, 90k tbn, 23.98 tbc (default)
  
          Metadata:
  
            creation_time   : 2019-07-15T08:22:53.000000Z
  
            handler_name    : Core Media Video
  
            encoder         : Lavc58.35.100 libx264
  
          Side data:
  
            cpb: bitrate max/min/avg: 428000/0/400000 buffer size: 600000 vbv_delay: -1
  
          Stream #0:1(und): Audio: aac (LC), 48000 Hz, stereo, fltp, 64 kb/s (default)
  
          Metadata:
  
            creation_time   : 2019-07-15T08:22:53.000000Z
  
            handler_name    : Core Media Audio
  
            encoder         : Lavc58.35.100 aac
  
      [libx264 @ 0x6501780] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
  
      Error initializing output stream 1:0 -- Error while opening encoder for output stream #1:0 - maybe incorrect parameters such as bit_rate, rate, width or heigh