Hello,
I found the reason. In my code, where i initialize the CodecContext and so on,
the are these lines from a former tutorial (former means here, where we use
av_read_packet instead of av_read_frame).
if(mPCodec->capabilities & CODEC_CAP_TRUNCATED)
mPCodecCtx->flags|=CODEC_FLAG_TRUNCATED;
So I remove these lines and voila! Heureka! It works.
regards,
Sven
Am Sonntag 11 Januar 2009 17:24 schrieb Sven Alisch:
> Hello,
>
> I have a strange problem and do not find a solution. I try to extract a
> serie of Pictures in a MPEG2-Transport-Stream. The I-Frames are nice and
> ok, but the other frames (P- and B-frames) are corrupted. My Code is the
> following:
>
> int i = 0; // Pic Nr.
> int frameFinished = 0;
>
> do
> {
> if (packet.stream_index == mStreamID) // at this step I've
> already read
> a packet!
> {
> int bytesRemaining = packet.size;
> int bytesDecoded = 0;
>
> bytesDecoded = avcodec_decode_video(mPCodecCtx, frame,
> &frameFinished, packet.data, packet.size);
>
> if (frameFinished)
> {
> i++;
>
> if (i == 12) // only 12 pictures for test
> return;
>
> cout << frame->pict_type << " dekodiert!" << endl;
>
> int numBytes=avpicture_get_size(PIX_FMT_RGB24, mPCodecCtx->width,
> mPCodecCtx->height);
> uint8_t* imgbuf = (uint8_t*) av_malloc(numBytes*sizeof(uint8_t));
>
> avpicture_fill((AVPicture *)pFrameRGB, imgbuf, PIX_FMT_RGB24,
> mPCodecCtx->width, mPCodecCtx->height);
>
> img_convert_ctx = sws_getContext(mPCodecCtx->width,
> mPCodecCtx->height,
> mPCodecCtx->pix_fmt,
> mPCodecCtx->width,
> mPCodecCtx->height,
> PIX_FMT_RGB24,
> SWS_BICUBIC, NULL, NULL, NULL);
> sws_scale(img_convert_ctx, frame->data, frame->linesize,
> 0, mPCodecCtx->height, pFrameRGB->data,
> pFrameRGB->linesize);
>
> // Bild als PPM speichern
> int flength = (mPCodecCtx->width * mPCodecCtx-> height * 3) + 15;
> rawframe = new uint8_t[flength+1];
> sprintf((char*)rawframe,"P6\n%d %d\n255\n", mPCodecCtx->width,
> mPCodecCtx->height);
>
> // dekodierten Bildinhalt kopieren
> int buf_stelle = 15; // Nach dem PPM-Bild-Header
> for(int y=0; y<mPCodecCtx->height; y++)
> {
> memcpy(&rawframe[buf_stelle],
> pFrameRGB->data[0]+y*pFrameRGB->linesize[0], mPCodecCtx->width*3);
> buf_stelle += mPCodecCtx->width*3;
> }
> flength = buf_stelle;
>
> ostringstream Str;
> Str << i;
>
> string filename = "pic" + Str.str() + ".ppm";
> FILE* fp = fopen(filename.c_str(),"wb");
> fwrite(rawframe, flength, 1, fp);
> fclose(fp);
> }
> }
>
> av_free_packet(&packet);
>
> } while (av_read_frame(mPAVFile->_formatContext(), &packet) >= 0);
>
> After the extraction I get only nice I-Frames. The rest of the pictures are
> corrupted. May anyone help me?
>
> regards,
> Sven
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