Hi Navin, Also YUV4:2:0 in BMP does not seem feasible (sorry for my previous statement). One think you can do too is use ffmpeg in a system call in your code. This is very versatile (you need to replace 422 by 420 though) char ffmpegString[256];//should be plenty char fmt[] = "bmp"; //bmp, jpg, png, pgm etc... sprintf(ffmpegString, "ffmpeg.exe -s %dx%d -vcodec rawvideo -f rawvideo -pix_fmt uyvy422 -i raw_uyvy422.yuv -f image2 raw_uyvy422.%s",RawWidth, RawHeight, fmt); system(ffmpegString);
Malik Cisse -----Original Message----- From: libav-user-boun...@ffmpeg.org [mailto:libav-user-boun...@ffmpeg.org] On Behalf Of Navin Sent: 20 November 2012 12:09 To: libav-user@ffmpeg.org Subject: Re: [Libav-user] get RGB values from ffmpeg frame Hey thanks everyone! Still trying/struggling with the code sent by Malik because avcodec_decode_video is deprecated. Thought I'd post the entire code here for anyone who could help or for anyone who needs such code in future. This is the corrected version of ffmpeg's tutorial02, with SDL added to it too. Problems are: 1. Since I was facing trouble with RGB, I thought I'd use SDL to output the frames as bitmaps, but although I could store the bitmap in an area in memory, it threw an exception when I tried extracting it out of memory. 2. Besides, when at least trying to output the bitmap to hard disk, I'm unable to output it unless SDL_DisplayYUVOverlay(bmp, &rect); is called (and I don't want to call it because I don't want the video to be displayed. I just want the bitmap to be output). 3. Main problem is still with extracting RGB, so would be grateful for any help. If not RGB, then at least with question 1 (how to store and extract the BMP from SDL memory). The code: extern "C" { #include <libavcodec/avcodec.h> #include <libavformat/avformat.h> #include <libswscale/swscale.h> } #include<iostream> #include <SDL.h> #include <SDL_thread.h> #include "SDL_opengl.h" #include <gl/gl.h> #include <gl/glu.h> //#ifdef __MINGW32__ #undef main /* Prevents SDL from overriding main() */ //#endif #include <stdio.h> //------------------------ // These functions should not be used except from pointers in a RWops static int myseekfunc(SDL_RWops *context, int offset, int whence) { SDL_SetError("Can't seek in this kind of RWops"); return(-1); } static int myreadfunc(SDL_RWops *context, void *ptr, int size, int maxnum) { memset(ptr,0,size*maxnum); return(maxnum); } static int mywritefunc(SDL_RWops *context, const void *ptr, int size, int num) { return(num); } static int myclosefunc(SDL_RWops *context) { if(context->type != 0xdeadbeef) { SDL_SetError("Wrong kind of RWops for myclosefunc()"); return(-1); } free(context->hidden.unknown.data1); SDL_FreeRW(context); return(0); } // Note that this function is NOT static -- we want it directly callable from other source files SDL_RWops *MyCustomRWop() { SDL_RWops *c=SDL_AllocRW(); if(c==NULL) return(NULL); c->seek =myseekfunc; c->read =myreadfunc; c->write=mywritefunc; c->close=myclosefunc; c->type =0xdeadbeef; printf("deadbeef=%d\n",c->type); c->hidden.unknown.data1=malloc(100000); return(c); } int main(int argc, char *argv[]) { AVFormatContext *pFormatCtx = NULL; int i, videoStream; AVCodecContext *pCodecCtx = NULL; AVCodec *pCodec = NULL; AVFrame *pFrame = NULL; AVPacket packet; int frameFinished; //float aspect_ratio; AVDictionary *optionsDict = NULL; struct SwsContext *sws_ctx = NULL; SDL_Overlay *bmp = NULL; SDL_Surface *screen = NULL; SDL_Surface *screen2 = NULL; SDL_Surface *rgbscreen = NULL; SDL_Rect rect; SDL_Event event; if(argc < 2) { fprintf(stderr, "Usage: test.exe <videofile>\n"); exit(1); } // Register all formats and codecs av_register_all(); if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) { fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError()); exit(1); } // Open video file if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0) return -1; // Couldn't open file // Retrieve stream information if(avformat_find_stream_info(pFormatCtx, NULL)<0) return -1; // Couldn't find stream information // Dump information about file onto standard error //av_dump_format(pFormatCtx, 0, argv[1], 0); // Find the first video stream videoStream=-1; for(i=0; i<pFormatCtx->nb_streams; i++) if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) { videoStream=i; break; } if(videoStream==-1) return -1; // Didn't find a video stream // Get a pointer to the codec context for the video stream pCodecCtx=pFormatCtx->streams[videoStream]->codec; // Find the decoder for the video stream pCodec=avcodec_find_decoder(pCodecCtx->codec_id); if(pCodec==NULL) { fprintf(stderr, "Unsupported codec!\n"); return -1;} // Codec not found // Open codec if(avcodec_open2(pCodecCtx, pCodec, &optionsDict) < 0) return -1; // Could not open codec // Allocate video frame pFrame = avcodec_alloc_frame(); #if defined(TRIAL) int width1 = pCodecCtx->width, height1 = pCodecCtx->height, width2 = pCodecCtx->width, height2 = pCodecCtx->height; struct SwsContext *resize = sws_getContext(width1, height1, PIX_FMT_YUV420P, width2, height2, PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL, NULL); AVFrame* frame1 = avcodec_alloc_frame(); // this is your original frame AVFrame* frame2 = avcodec_alloc_frame(); int num_bytes = avpicture_get_size(PIX_FMT_RGB24, width2, height2); uint8_t* frame2_buffer = (uint8_t *) av_malloc(num_bytes * sizeof(uint8_t)); #endif // Make a screen to put our video #ifndef __DARWIN__ screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0); #else screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0); #endif if(!screen) { fprintf(stderr, "SDL: could not set video mode - exiting\n"); exit(1); } // Allocate a place to put our YUV image on that screen bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height, SDL_YV12_OVERLAY, screen); sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BILINEAR, NULL, NULL, NULL ); // Read frames and save first five frames to disk i=0; while(av_read_frame(pFormatCtx, &packet) >= 0) { // Is this a packet from the video stream? if(packet.stream_index==videoStream) { // Decode video frame avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet); // Did we get a video frame? if(frameFinished) { #if defined(TRIAL) avpicture_fill((AVPicture*) frame2, frame2_buffer, PIX_FMT_RGB24, width2, height2); printf("data = %d \n",frame2->data[0]); printf("linesize = %d %d %d\n",frame2->linesize[0], frame2->linesize[1], frame2->linesize[2]); printf("width = %d\n", pCodecCtx->width); printf("height = %d\n", pCodecCtx->height); std::cin.get(); int linesize = frame2->linesize[0]; for(int xx = 0; xx < (linesize * width1)-1; xx += 3) { int r = frame2->data[0][xx];//int r = frame2->data[0][xx]; int g = frame2->data[0][xx+1]; int b = frame2->data[0][xx+2]; printf("xx=%d r=%d, g=%d, b=%d \n",xx, r, g, b); } printf("frame%d done----------------",i++); //for(int xx = 0; xx < width1; xx = xx + 3) //{ // for(int yy = 0; yy < height1; ++yy) // { // //int p = xx*3 + yy*frame2->linesize[0]; // //int p = xx * 3 + yy * linesize; // printf("yy=%d xx=%d",yy,xx); // int p = yy * linesize + xx; // printf("p=%d\n",p); // int r = frame2->data[0][p]; // int g = frame2->data[0][p+1]; // int b = frame2->data[0][p+2]; // printf("[r=%d, g=%d, b=%d ]\n", r, g, b); // }//for //}//for // frame1 should be filled by now (eg using avcodec_decode_video) sws_scale(resize, frame1->data, frame1->linesize, 0, height1, frame2->data, frame2->linesize); #endif SDL_LockYUVOverlay(bmp);//-----------lock AVPicture pict; pict.data[0] = bmp->pixels[0]; pict.data[1] = bmp->pixels[2]; pict.data[2] = bmp->pixels[1]; pict.linesize[0] = bmp->pitches[0]; pict.linesize[1] = bmp->pitches[2]; pict.linesize[2] = bmp->pitches[1]; // Convert the image into YUV format that SDL uses sws_scale( sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pict.data, pict.linesize ); SDL_UnlockYUVOverlay(bmp);//-----------unlock rect.x = 0; rect.y = 0; rect.w = pCodecCtx->width; rect.h = pCodecCtx->height; SDL_DisplayYUVOverlay(bmp, &rect); //printf("sizeof screen = %d\n",sizeof(*screen)); if (++i != 0) { char numberbuffer [33], str[80]; strcpy (str, "bitmap"); strcat (str, itoa(i, numberbuffer, 10)); strcat (str, ".bmp");//file for storing image //---------this saves it as a bitmap to filestream. But now how to extract it? //SDL_RWops *filestream = MyCustomRWop();//SDL_AllocRW(); //SDL_SaveBMP_RW (screen, filestream, i); //screen2 = SDL_LoadBMP_RW(filestream,1);//LOADING IS THE PROBLEM HERE. DON'T KNOW WHY //filestream->close; //SDL_SaveBMP(screen2, str); SDL_SaveBMP(screen, str);//WORKS: saves frame to a file as a bitmap } }//if(frameFinished) }//if // Free the packet that was allocated by av_read_frame av_free_packet(&packet); SDL_PollEvent(&event); switch(event.type) { case SDL_QUIT: SDL_Quit(); exit(0); break; default: break; }//switch }//while av_free(pFrame);// Free the YUV frame avcodec_close(pCodecCtx);// Close the codec avformat_close_input(&pFormatCtx);// Close the video file return 0; }//main Nav On 11/20/2012 3:38 PM, Carl Eugen Hoyos wrote: > Navin<nkipe@...> writes: > >> I have been through many websites, but they either use >> img_convert (which doesn't work) or sws_scale, which >> crashes when I try to use it with RGB. > I may miss something, but I guess this is the important > problem you should work on (see doc/examples). > > Possibly unrelated: > In your source code, I did not find information which > decoder you are using. > Some decoders (everything mpeg-related) output yuv, and > if you want the data in rgb, you have to convert it > (using the sofware scaler), others (some lossless formats) > output rgb, that may already be the data you want. > > Carl Eugen > > _______________________________________________ > Libav-user mailing list > Libav-user@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/libav-user > _______________________________________________ Libav-user mailing list Libav-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/libav-user _______________________________________________ Libav-user mailing list Libav-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/libav-user