>-----Original Message----- >From: [email protected] [mailto:libav-user- >[email protected]] On Behalf Of Stefano Sabatini >Sent: 6. marraskuuta 2012 2:32 >To: This list is about using libavcodec, libavformat, libavutil, libavdevice and >libavfilter. >Subject: Re: [Libav-user] How can we set frame size for live stream? > >> Hi, >> >> I use the USB camera to capture live video. >> >> The default codec context is: >> Input #0, dshow, from 'video=Mercury USB2.0 Camera': >> Duration: N/A, start: 58890.453000, bitrate: N/A >> Stream #0:0: Video: mjpeg, yuvj422p, 1280x720, 30 tbr, 10000k tbn, >> 30 tbc >> >> I hope to change frame size from 1280x720 to 640x480. >> >> I tried >> AVCodecContext >> pCodecCtx->width = 640; >> pCodecCtx->height = 480; >> >> But this did not work. > >You can set the options in the dshow device, using the *private* option >"video_size": >http://ffmpeg.org/ffmpeg.html#dshow > >Note that the input device may not honour the exact video size, or may >choose a video size that is "reasonably" similar to the one requested (need to >check the code for that, documentation updates are welcome). > >From a programmatic point of view, you need to set the options for the input >format context in a dictionary and pass it to avformat_open_input(), >something like: > >AVDictionary *options = NULL; >av_dict_set(&options, "video_size", "640x480", 0); av_dict_set(&options, >"pixel_format", "rgb24", 0); > >if (avformat_open_input(&s, url, NULL, &options) < 0) > abort(); >... >av_dict_free(&options); > >Check avformat.h doxy for more information.
Hi Stefano, Thanks very much ! This is really what I want. _____________________________________________ >Libav-user mailing list >[email protected] >http://ffmpeg.org/mailman/listinfo/libav-user _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
