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  • Why doesn't this FFmpeg code create a video from a series of images ?

    20 octobre 2011, par user551117

    I have successfully compiled the FFmpeg library for use in an iOS application. I would like to use it for encoding a video from a series of images, but I can't seem to make it work.

    The following is the code that I am using to encode this video:

    AVCodec *codec;
AVCodecContext *c= NULL;
int i, out_size, size, outbuf_size;
FILE *f;
AVFrame *picture;
uint8_t *outbuf;

printf("Video encoding\n");

/// find the mpeg video encoder
codec=avcodec_find_encoder(CODEC_ID_MPEG4);
//codec = avcodec_find_encoder(CODEC_ID_MPEG4);
if (!codec) {
    fprintf(stderr, "codec not found\n");
    exit(1);
}

c= avcodec_alloc_context();
picture= avcodec_alloc_frame();

// put sample parameters 
c->bit_rate = 400000;
/// resolution must be a multiple of two 
c->width = 320;
c->height = 480;
//frames per second 
c->time_base= (AVRational){1,25};
c->gop_size = 10; /// emit one intra frame every ten frames
c->max_b_frames=1;
c->pix_fmt = PIX_FMT_YUV420P;

//open it
if (avcodec_open(c, codec) < 0) {
    fprintf(stderr, "could not open codec\n");
    exit(1);
}

f = fopen([[NSTemporaryDirectory() stringByAppendingPathComponent:filename] UTF8String], "w");
if (!f) {
    fprintf(stderr, "could not open %s\n",[filename UTF8String]);
    exit(1);
}

// alloc image and output buffer
outbuf_size = 100000;
outbuf = malloc(outbuf_size);
size = c->width * c->height;

#pragma mark -
AVFrame* outpic = avcodec_alloc_frame();
int nbytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);

//create buffer for the output image
uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes);

#pragma mark -  
for(i=1;i<48;i++) {
    fflush(stdout);

    int numBytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);
    uint8_t *buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));

    UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"%d.png", i]];
    CGImageRef newCgImage = [image CGImage];

    CGDataProviderRef dataProvider = CGImageGetDataProvider(newCgImage);
    CFDataRef bitmapData = CGDataProviderCopyData(dataProvider);
    buffer = (uint8_t *)CFDataGetBytePtr(bitmapData);   

    avpicture_fill((AVPicture*)picture, buffer, PIX_FMT_RGB24, c->width, c->height);
    avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, c->width, c->height);

    struct SwsContext* fooContext = sws_getContext(c->width, c->height, 
                                                   PIX_FMT_RGB24, 
                                                   c->width, c->height, 
                                                   PIX_FMT_YUV420P, 
                                                   SWS_FAST_BILINEAR, NULL, NULL, NULL);

    //perform the conversion
    sws_scale(fooContext, picture->data, picture->linesize, 0, c->height, outpic->data, outpic->linesize);
    // Here is where I try to convert to YUV

    // encode the image

    out_size = avcodec_encode_video(c, outbuf, outbuf_size, outpic);
    printf("encoding frame %3d (size=%5d)\n", i, out_size);
    fwrite(outbuf, 1, out_size, f);

    free(buffer);
    buffer = NULL;      

}

// get the delayed frames
for(; out_size; i++) {
    fflush(stdout);

    out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
    printf("write frame %3d (size=%5d)\n", i, out_size);
    fwrite(outbuf, 1, outbuf_size, f);      
}

// add sequence end code to have a real mpeg file
outbuf[0] = 0x00;
outbuf[1] = 0x00;
outbuf[2] = 0x01;
outbuf[3] = 0xb7;
fwrite(outbuf, 1, 4, f);
fclose(f);
free(outbuf);

avcodec_close(c);
av_free(c);
av_free(picture);
printf("\n");

    What could be wrong with this code?

  • Why does FFMPEG reports the wrong duration ?

    20 octobre 2011, par Adrian Lynch

    I have an oldish build of FFMPEG that I can't easily change.

    We use FFMPEG to find the duration of video and sound files. So far it has been working wonderfully.

    Recently on an uploaded file, FFMPEG has reported a 30 second file as being 5 minutes 30 seconds in length.

    Could it be something wrong with the file rather than FFMPEG?

    If I use FFMPEG to convert to another file, the duration is restored.

    In case it matters, ffmpeg -i 'path to the file' produces:

        FFmpeg version Sherpya-r15618, Copyright (c) 2000-2008 Fabrice Bellard, et al.
      libavutil     49.11. 0 / 49.11. 0
      libavcodec    52. 0. 0 / 52. 0. 0
      libavformat   52.22. 1 / 52.22. 1
      libavdevice   52. 1. 0 / 52. 1. 0
      libswscale     0. 6. 1 /  0. 6. 1
      libpostproc   51. 2. 0 / 51. 2. 0
      built on Oct 14 2008 23:43:47, gcc: 4.2.5 20080919 (prerelease) [Sherpya]
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'H:\path\to\file.mov':
      Duration: 00:05:35.00, start: 0.000000, bitrate: 1223 kb/s
        Stream #0.0(eng): Audio: aac, 44100 Hz, stereo, s16
        Stream #0.1(eng): Video: h264, yuv420p, 720x576, 25.00 tb(r)
    Must supply at least one output file

    It's that very command I use to then extract the duration with RegEx.

    Does anyone have a nice application that can do what I'm trying above but get it right 100% of the time?

  • Strange issue with FFMPEG

    19 octobre 2011, par Raphael Milani

    I´ve been facing a strange issue with ffmpeg. I´ve tried converting videos MP4 to FLV but the ffpmeg doesn´t convert the whole of video. For example if the video has 10min the ffmpeg only converts 09 min and 30 seconds. I´ve been using this command to convert: 

     -y -i "<$InFilePath$>" -ab 56 -ar 44100 -b 900000 -r 30 -s 832X468 -aspect 16:9 -f flv -qscale 2 "<$OutFilePath$>"

    Has anyone faced this problem?

  • ffmpeg from erlang using open_port

    19 octobre 2011, par user1002473

    I've got a problem with ffmpeg, when I try to use it in pipe to pipe mode in erlang. This's my code list:

    fun(Data) ->
    Port = open_port(
        {spawn, "ffmpeg -i -  -acodec copy -vcodec copy -f flv - "},
        [binary,stream,use_stdio,exit_status]
    ),
    Port ! {self(),{command,<binary>>}},
    receive_data(Port).

    and I've got this error from std error:

    av_interleaved_write_frame(): Broken pipe

  • How to convert .flv file to .3gp using ffmpeg ? [migrated]

    19 octobre 2011, par Chetana

    I have converted any video format to 3gp file format using ffmpeg on one server. But on another server it not works.

    Following is my script:

    exec("ffmpeg -i test.flv -sameq -acodec libmp3lame -ar 22050 -ab 96000
    -deinterlace -nr 500 -s 320x240 -aspect 4:3 -r 20 -g 500 -me_range 20
    -b 270k -deinterlace -f flv -y test.3gp ");

    Can anyone tell me what is wrong in script?

    Following is my ffmpeg setting:

    root@ninja [~]# ffmpeg -formats ffmpeg version CVS, build 3277056, Copyright (c) 2000-2004 Fabrice Bellard configuration: --enable-mp3lame --enable-libogg --enable-gpl --disable-mmx --enable-shared built on Jun 17 2009 10:51:43, gcc: 4.1.2 20080704 (Red Hat 4.1.2-44)

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