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• Evolution #3849 : Affiner/retirer les disallow de robots.txt qui empêchent les sites SPIP de se ré...

  28 octobre 2016, par Spipmalion Dupond

  Merci pour ta réponse
  Effectivement, je viens d’activer la compression et cela va régler la plupart des problèmes d’accès par Google

  C’est quand même embêtant pour les sites qui n’activent pas la compression puisqu’elle n’est pas obligatoire, et aussi la compression ne compresse pas 100% des fichiers chez moi : http://forum.spip.net/fr_265551.html

• 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.