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POFFmpeg: avcodec_encode_video() and JPEG images
 

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  1. POFFmpeg: avcodec_encode_video() and JPEG images
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    <p>I'm trying to encode a series of .jpg files into a video using the ffmpeg library, and I can't seem to get the frames to encode. (I have to use the ffmpeg library, and using ffmpeg from a command line is not an option in my case.)</p> <p>Except for the part where I'm trying to open JPG files as AVFrames, my code is more or less the same thing as found in api-example.c from the ffmpeg library. When I populate the frames as the example does, everything works as expected. In the code below, I fail to encode any frames. Obviously the trouble is related to how I'm opening the JPG files, but I can't figure out what.</p> <p>I'm opening the image like this:</p> <pre><code>AVFrame* open_image(const char* imageFileName, int width, int height, long * bufSize) { AVFormatContext *pFormatCtx; if(av_open_input_file(&amp;pFormatCtx, imageFileName, NULL, 0, NULL)!=0) { printf("Can't open image file '%s'\n", imageFileName); return NULL; } AVCodecContext *pCodecCtx; pCodecCtx = pFormatCtx-&gt;streams[0]-&gt;codec; pCodecCtx-&gt;width = width; pCodecCtx-&gt;height = height; pCodecCtx-&gt;pix_fmt = PIX_FMT_YUV420P; // Find the decoder for the video stream AVCodec *pCodec = avcodec_find_decoder(pCodecCtx-&gt;codec_id); if (!pCodec) { printf("Codec not found\n"); return NULL; } // Open codec if(avcodec_open(pCodecCtx, pCodec)&lt;0) { printf("Could not open codec\n"); return NULL; } AVFrame *pFrame = avcodec_alloc_frame(); if (!pFrame) { LOGV(TAG, "Can't allocate memory for AVFrame\n"); return NULL; } int frameFinished; int numBytes; // Determine required buffer size and allocate buffer numBytes = avpicture_get_size(PIX_FMT_YUVJ420P, pCodecCtx-&gt;width, pCodecCtx-&gt;height); // *** *bufSize = numBytes; // *** uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t)); avpicture_fill((AVPicture *) pFrame, buffer, PIX_FMT_YUVJ420P, pCodecCtx-&gt;width, pCodecCtx-&gt;height); // Read frame AVPacket packet; int framesNumber = 0; while (av_read_frame(pFormatCtx, &amp;packet) &gt;= 0) { if(packet.stream_index != 0) continue; int ret = avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet); if (ret &gt; 0) { sprintf(buf, "Frame is decoded, size %d", ret); LOGV(TAG, buf); pFrame-&gt;quality = 4; return pFrame; } else { // printf("Error [%d] while decoding frame: %s\n", ret, strerror(AVERROR(ret))); sprintf(buf, "Error %d decoding frame: %s", ret, strerror(AVERROR(ret))); LOGV(TAG, buf); } } } </code></pre> <p>...and attempting to encode them like this:</p> <pre><code>DIR * dir = opendir(path); int i = 0; if (dir != NULL) { for(struct dirent *ent = readdir(dir); ent != NULL; ent = readdir(dir)) { fflush(stdout); printf("%s/%s", path, ent-&gt;d_name); LOGV(TAG, filename); // If not a jpg file, pass it over const char * ext = strrchr(filename, '.'); if((!ext) || (strcmp(ext, ".jpg"))) { continue; } /*** NOTE: Is this where I've gone wrong? Bufsize is set in open_image based on av_picture_size() */ long bufSize = 0L; AVFrame * frame = open_image(filename, width, height, &amp;bufSize); if(frame) { // This is what it needs to do, and it does not work. // Causes: // Wrong format? // Wrong buffer size? uint8_t * picBuf = (uint8_t *)malloc(bufSize); out_size = avcodec_encode_video(c, picBuf, bufSize, frame); printf("encoding frame %3d (size=%5d)\n", i++, out_size); /** On the first image, out_size is 0. On the next, it's -1, and fails. */ if(out_size &lt; 0) { printf("Error encoding frame"); return -6; } fwrite(picBuf, 1, bufSize, f); free(picBuf); av_free(frame); } else { printf("Couldn't open image"); return -5; } } closedir(dir); } else { printf("Couldn't open directory %s\n", path); return -4; } </code></pre> <p>Could someone point me in the right direction? </p>
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