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• ffmpeg - dump_format() function print out 00:00:00

  16 juin 2013, par Juneyoung Oh

  I am working with ffmpeg.

  The only function that I needed is just extract duration of video on memory, not console.

  to do this, I realized that I have to redesign dump_format() function

  witch defined in avformat.h.

  below is the original source and especially what I need is dump_format

  that located in line 3063.

  http://ffmpeg.org/doxygen/0.6/libavformat_2utils_8c-source.html#l03063

  when I use dump_format, it returns everything fine but except duration.

  duration always returns 00:00:00.

  below is my test code. When I call line 31 is fine, but not 32.

  I want know what is wrong with my code.

  I suspect the fact that I dropped function dump_metadata.

  But everytime I use that function console prints undefined function error.

    1 #include <libavcodec></libavcodec>avcodec.h>
  
    2 #include <libavformat></libavformat>avformat.h>
  
    3 #include 
  
    4 #include 
  
    5 #include 
  
    6 
  
    7 void dump_format1(AVFormatContext* ic, int index, const char* url, int is_output);
  
    8 
  
    9 int main(int argc, char *argv[]) {
  
   10         AVFormatContext* pFormatCtx;
  
   11         int secs;
  
   12         //need those for printing...
  
   13 
  
   14         if(argc &lt; 2) {
  
   15                 printf("Please provide a movie file\n");
  
   16                 return -1;
  
   17         }
  
   18         //threat Exception for arguements.
  
   19 
  
   20         av_register_all();
  
   21         //register all codecs
  
   22 
  
   23         //========== Check Context
  
   24         if(av_open_input_file(&amp;pFormatCtx, argv[1], NULL, 0, NULL) != 0)
  
   25                 return -1;
  
   26 
  
   27         if(av_find_stream_info(pFormatCtx) &lt; 0)
  
   28                 return -1;
  
   29 
  
   30         //========== Print Basic Information
  
   31         //dump_format(pFormatCtx, 0 , argv[1], 0);
  
   32         dump_format1(pFormatCtx, 0 , argv[1], 0);
  
   33 
  
   34 
  
   35         if(pFormatCtx->duration != AV_NOPTS_VALUE){
  
   36                 secs = (pFormatCtx->duration) / AV_TIME_BASE;
  
   37         }
  
   38 
  
   39         /*
  
   40                 AV_TIME_BASE = 1000000
  
   41         */
  
   42 
  
   43         printf("%d\n",secs);
  
   44 
  
   45         return 0;
  
   46 }
  
   47 
  
   48 void dump_format1(AVFormatContext *ic,
  
   49                   int index,
  
   50                   const char *url,
  
   51                   int is_output) {
  
   52 
  
   53         int i;
  
   54         uint8_t *printed = av_mallocz(ic->nb_streams);
  
   55         if (ic->nb_streams &amp;&amp; !printed)
  
   56                 return;
  
   57 
  
   58         av_log(NULL, AV_LOG_INFO, "%s #%d, %s, %s &#39;%s&#39;:\n",
  
   59         is_output ? "Output" : "Input",
  
   60         index,
  
   61         is_output ? ic->oformat->name : ic->iformat->name,
  
   62         is_output ? "to" : "from", url);
  
   63 
  
   64         dump_metadata(NULL, ic->metadata, "  ");
  
   65 
  
   66         //if (!is_output) {
  
   67         av_log(NULL, AV_LOG_INFO, "  Duration: ");
  
   68 
  
   69 
  
   70 
  
   71 
  
   72         int hours, mins, secs, us;
  
   73         secs = ic->duration / AV_TIME_BASE;
  
   74         us = ic->duration % AV_TIME_BASE;
  
   75         mins = secs / 60;
  
   76         secs %= 60;
  
   77         hours = mins / 60;
  
   78         mins %= 60;
  
   79         av_log(NULL, AV_LOG_INFO, "%02d:%02d:%02d.%02d", hours, mins, secs,
  
   80         (100 * us) / AV_TIME_BASE);
  
   81         return;
  
   82 }

  I compile with following commands.

  gcc -o tutorial01 tutorial01.c -lavformat -lavcodec -lswscale -lz
  ./tutorial01 /home/juneyoungoh/Videos/CON1234ID.ts

  Thanks for your guidences in advance.

• How AVCodecContext bitrate, framerate and timebase is used when encoding single frame

  28 mars 2023, par Cyrus

  I am trying to learn FFmpeg from examples as there is a tight schedule. The task is to encode a raw YUV image into JPEG format of the given width and height. I have found examples from ffmpeg official website, which turns out to be quite straight-forward. However there are some fields in AVCodecContext that I thought only makes sense when encoding videos(e.g. bitrate, framerate, timebase, gopsize, max_b_frames etc).

  


  I understand on a high level what those values are when it comes to videos, but do I need to care about those when I just want a single image ? Currently for testing, I am just setting them as dummy values and it seems to work. But I want to make sure that I am not making terrible assumptions that will break in the long run.

  


  EDIT :

  


  Here is the code I got. Most of them are copy and paste from examples, with some changes to replace old APIs with newer ones.

  


  #include "thumbnail.h"
#include "libavcodec/avcodec.h"
#include "libavutil/imgutils.h"
#include 
#include 
#include 

void print_averror(int error_code) {
    char err_msg[100] = {0};
    av_strerror(error_code, err_msg, 100);
    printf("Reason: %s\n", err_msg);
}

ffmpeg_status_t save_yuv_as_jpeg(uint8_t* source_buffer, char* output_thumbnail_filename, int thumbnail_width, int thumbnail_height) {
    const AVCodec* mjpeg_codec = avcodec_find_encoder(AV_CODEC_ID_MJPEG);
    if (!mjpeg_codec) {
        printf("Codec for mjpeg cannot be found.\n");
        return FFMPEG_THUMBNAIL_CODEC_NOT_FOUND;
    }

    AVCodecContext* codec_ctx = avcodec_alloc_context3(mjpeg_codec);
    if (!codec_ctx) {
        printf("Codec context cannot be allocated for the given mjpeg codec.\n");
        return FFMPEG_THUMBNAIL_ALLOC_CONTEXT_FAILED;
    }

    AVPacket* pkt = av_packet_alloc();
    if (!pkt) {
        printf("Thumbnail packet cannot be allocated.\n");
        return FFMPEG_THUMBNAIL_ALLOC_PACKET_FAILED;
    }

    AVFrame* frame = av_frame_alloc();
    if (!frame) {
        printf("Thumbnail frame cannot be allocated.\n");
        return FFMPEG_THUMBNAIL_ALLOC_FRAME_FAILED;
    }

    // The part that I don't understand
    codec_ctx->bit_rate = 400000;
    codec_ctx->width = thumbnail_width;
    codec_ctx->height = thumbnail_height;
    codec_ctx->time_base = (AVRational){1, 25};
    codec_ctx->framerate = (AVRational){1, 25};

    codec_ctx->gop_size = 10;
    codec_ctx->max_b_frames = 1;
    codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
    int ret = av_image_fill_arrays(frame->data, frame->linesize, source_buffer, AV_PIX_FMT_YUV420P, thumbnail_width, thumbnail_height, 32);
    if (ret < 0) {
        print_averror(ret);
        printf("Pixel format: yuv420p, width: %d, height: %d\n", thumbnail_width, thumbnail_height);
        return FFMPEG_THUMBNAIL_FILL_FRAME_DATA_FAILED;
    }

    ret = avcodec_send_frame(codec_ctx, frame);
    if (ret < 0) {
        print_averror(ret);
        printf("Failed to send frame to encoder.\n");
        return FFMPEG_THUMBNAIL_FILL_SEND_FRAME_FAILED;
    }

    ret = avcodec_receive_packet(codec_ctx, pkt);
    if (ret < 0) {
        print_averror(ret);
        printf("Failed to receive packet from encoder.\n");
        return FFMPEG_THUMBNAIL_FILL_SEND_FRAME_FAILED;
    }

    // store the thumbnail in output
    int fd = open(output_thumbnail_filename, O_CREAT | O_RDWR);
    write(fd, pkt->data, pkt->size);
    close(fd);

    // freeing allocated structs
    avcodec_free_context(&codec_ctx);
    av_frame_free(&frame);
    av_packet_free(&pkt);
    return FFMPEG_SUCCESS;
}


  


• No such file or directory : 'ffprobe' : 'ffprobe'

  27 novembre 2023, par Jack McCumber

  I'm hoping someone can point me in the right direction. I'm currently trying to build a python GUI that plays clips of sounds from a specified file and allows the user to annotate it. All the research I've done has pointed my to using pydub. I'm using the following snippet :

  


  from pydub import AudioSegment
from pydub.playback import play

song = AudioSegment.from_wav("beepboop.mp3")
play(song)


  


  However, I'm currently getting the following error :

  


  Warning (from warnings module):&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pydub/utils.py", line 170&#xA;    warn("Couldn&#x27;t find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)&#xA;RuntimeWarning: Couldn&#x27;t find ffmpeg or avconv - defaulting to ffmpeg, but may not work&#xA;&#xA;Warning (from warnings module):&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pydub/utils.py", line 198&#xA;    warn("Couldn&#x27;t find ffprobe or avprobe - defaulting to ffprobe, but may not work", RuntimeWarning)&#xA;RuntimeWarning: Couldn&#x27;t find ffprobe or avprobe - defaulting to ffprobe, but may not work&#xA;Traceback (most recent call last):&#xA;  File "/Users/jack/Desktop/code-repo/convert-csv-to-json/cleaner.py", line 7, in <module>&#xA;    song = AudioSegment.from_wav("beepboop.mp3")&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pydub/audio_segment.py", line 808, in from_wav&#xA;    return cls.from_file(file, &#x27;wav&#x27;, parameters=parameters)&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pydub/audio_segment.py", line 728, in from_file&#xA;    info = mediainfo_json(orig_file, read_ahead_limit=read_ahead_limit)&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pydub/utils.py", line 274, in mediainfo_json&#xA;    res = Popen(command, stdin=stdin_parameter, stdout=PIPE, stderr=PIPE)&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 775, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 1522, in _execute_child&#xA;    raise child_exception_type(errno_num, err_msg, err_filename)&#xA;FileNotFoundError: [Errno 2] No such file or directory: &#x27;ffprobe&#x27;: &#x27;ffprobe&#x27;&#xA;</module>

  


  I've downloaded both ffprobe and ffmpeg from the official website, extracted the files, and installed to usr/local/bin based on input I've read in other StackOverflow comments. When I run :

  


  print(os.environ['PATH'])


  


  I get :

  


  /usr/bin:/bin:/usr/sbin:/sbin


  


  Also, MacOSX won't let me manually drag the executable into /usr/bin or /usr/sbin. Nor will it let me copy it into the directory using :

  


  $ sudo cp ffmpeg /usr/bin


  


  When I use :

  


  pip3 install ffprobe-python


  


  I get :

  


  Requirement already satisfied: ffprobe-python in /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages (1.0.3)


  


  I'll add that when I try and use the "apt install" method, it barks at me and says my version of MacOSX isn't supported.