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• FFmpeg sample code for creating a video file from still images JNI Android

  21 juin 2012, par anish

  How i modify the following FFMPEG sample code for creating a video file from still images that i am having in my android phone. I am using JNI for invoking ffmpeg.

  JNIEXPORT void JNICALL videoEncodeExample((JNIEnv *pEnv, jobject pObj, jstring filename)
  
  
  
      {
  
       AVCodec *codec;
  
       AVCodecContext *c= NULL;
  
       int i, out_size, size, x, y, outbuf_size;
  
       FILE *f;
  
       AVFrame *picture;
  
       uint8_t *outbuf, *picture_buf;
  
  
  
       printf("Video encoding\n");
  
  
  
       /* find the mpeg1 video encoder */
  
       codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
  
       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 = 352;
  
       c->height = 288;
  
       /* 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(filename, "wb");
  
       if (!f) {
  
           fprintf(stderr, "could not open %s\n", filename);
  
           exit(1);
  
       }
  
  
  
       /* alloc image and output buffer */
  
       outbuf_size = 100000;
  
       outbuf = malloc(outbuf_size);
  
       size = c->width * c->height;
  
       picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
  
  
  
       picture->data[0] = picture_buf;
  
       picture->data[1] = picture->data[0] + size;
  
       picture->data[2] = picture->data[1] + size / 4;
  
       picture->linesize[0] = c->width;
  
       picture->linesize[1] = c->width / 2;
  
       picture->linesize[2] = c->width / 2;
  
  
  
       /* encode 1 second of video */
  
       for(i=0;i<25;i++) {
  
           fflush(stdout);
  
           /* prepare a dummy image */
  
           /* Y */
  
           for(y=0;yheight;y++) {
  
               for(x=0;xwidth;x++) {
  
                   picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
               }
  
           }
  
  
  
           /* Cb and Cr */
  
           for(y=0;yheight/2;y++) {
  
               for(x=0;xwidth/2;x++) {
  
                   picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
                   picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
               }
  
           }
  
  
  
           /* encode the image */
  
           out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
           printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
           fwrite(outbuf, 1, out_size, f);
  
       }
  
  
  
       /* 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, out_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(picture_buf);
  
       free(outbuf);
  
  
  
       avcodec_close(c);
  
       av_free(c);
  
       av_free(picture);
  
       printf("\n");
  
      }

  Thanks and Regards
  Anish

• ffmpeg h.264 video plays in Safari but not in Chrome

  6 mars 2016, par ensnare

  I’m using ffmpeg to encode a .MOV raw video into a compressed H.264 video for display on an html5 website. I’m using the below string to encode the video :

  ffmpeg -y \
  
  -i in.mov
  
  -b 3500k -bt 4000k \
  
  -acodec libfaac -ac 2 -ar 48000 -ab 192k \
  
  -vcodec libx264 -vpre ultrafast -vpre baseline \
  
  out.mp4

  The resulting video looks great and plays fine in Safari, but Chrome can’t recognize it. Any ideas ?

  Thanks.

• encoding a video for looping ?

  24 janvier 2013, par bennettk

  This is somewhat related to Looping a video with AVFoundation AVPlayer but that question is answered. What I'm trying to achieve is seamless looping using an AVPlayer. There is a noticeable stutter between loops using h264-encoded videos* that has gotten worse for some reason with the update to iOS 5. Could this have something to do with the way the videos are encoded rather than the AVPlayer ? The looping is triggered by a playerItemDidReachEnd notification as described in the link above.

  Thanks.

  * here's the ffmpeg command we're using to encode the videos, if that helps :

  ffmpeg -i -y -sameq -vcodec libx264 -vpre hq -crf 20 -an

  (yes, the files don't have sound (yet) so the -an is intentional.)