Newest 'ffmpeg' Questions - Stack Overflow
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FFMPEG : Explain parameters of any codecs fuction pointers
3 décembre 2013, par ZaxI'm going through the article, How to integrate a codec in FFMPEG multimedia framework. According to it, every codec needs to have 3 basic functions to be defined and these functions are assigned to function pointers of the structure
AVCodec.The 3 function pointers specified in the above article are:
.init -> takes care of allocations and other initializations .close -> freeing the allocated memory and de-initializations .decode -> frame by frame decoding.For the function pointer
.decode, the funtion assigned is:static int cook_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size) { ...The details of these parameters are specified in the above article. However, in the latest code, when the same function is taken as an example, its declaration is as shown below:
static int cook_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)I need to perform some mapping operations on the memory. So, i request if anyone could kindly explain the above parameters in the function declarations. Also, which parameter has the input buffer for decoding the frame? And after decoding a frame, to which parameter is the decoded frame mapped?
Thanks in advance.
-Regards.
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FFmpeg convert time to frame
3 décembre 2013, par William SeemannDoes anyone know how to convert a timestamp into a frame? For example, if I wanted the frame number at 2 seconds in a video with a framerate of 30/fps it would be the 60th frame. Here is the code I have so far. However, I don't think it's correct since seek_time has a value of 90 (for a 1 sec target) using a video with a framerate of 23.98:
int timeUs = 1000000; // 1 sec AVPacket packet; AVPacket *pkt = NULL; int64_t desired_frame_number = -1; State *state = *ps; Options opt = option; int stream_index = state->video_stream; int64_t seek_time = av_rescale_q(timeUs, AV_TIME_BASE_Q, state->pFormatCtx->streams[stream_index]->time_base); int64_t seek_stream_duration = state->pFormatCtx->streams[stream_index]->duration; int flags = 0; int ret = -1; // Convert time into frame number seek_time /= 1000; printf("seek time: %" PRId64 "\n", seek_time); -
using ffmpeg command line with python's subprocess module [on hold]
3 décembre 2013, par user1485853I have few wav files that I can use either of the following command line mentioned here to concatenate
ffmpeg -f concat -i <(for f in ./*.wav; do echo "file '$f'"; done) -c copy output.wav ffmpeg -f concat -i <(printf "file '%s'\n" ./*.wav) -c copy output.wav ffmpeg -f concat -i <(find . -name '*.wav' -printf "file '%p'\n") -c copy output.wavanyone know how to convert either of them to work with python's subprocess module, it would be better if your solution is platform independent .
the <(...) notation does is create a temporary file to contain the result, and inserts that file name on the command line. so is there any way to create a temporary file by Python here ?
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MPMoviePlayerController and Multiple Audio Streams in a MP4
3 décembre 2013, par Armin MI have an MP4 video with three audio streams for different languages, but when I choose between languages during the playback, the audio stream doesn't switch. What am I missing?
Here's how I'm playing the video:
MPMoviePlayerViewController *player = [[MPMoviePlayerViewController alloc] initWithContentURL:videoURL]; [self presentMoviePlayerViewControllerAnimated:player]; -
ffmpeg & png watermark issue
2 décembre 2013, par mindcastI tried to create a watermark (using a
pngimage) on a video like this:ffmpeg -i test.wmv -b:a 300k -ar 22050 -t 10 -f flv -s 352x288 -vf "movie = watermark_logo352.png [watermark]; [in][watermark] overlay =0:0 [out]" out.flvbut I get the error:
ffmpeg version 0.10.4 Copyright (c) 2000-2012 the FFmpeg developers built on Jun 14 2012 13:14:31 with gcc 4.4.5 configuration: --prefix=/home/username --enable-cross-compile --enable-shared --arch=amd64 --target-os=linux --disable-yasm --enable-decoder=png --enable-encoder=png libavutil 51. 35.100 / 51. 35.100 libavcodec 53. 61.100 / 53. 61.100 libavformat 53. 32.100 / 53. 32.100 libavdevice 53. 4.100 / 53. 4.100 libavfilter 2. 61.100 / 2. 61.100 libswscale 2. 1.100 / 2. 1.100 libswresample 0. 6.100 / 0. 6.100 Input #0, asf, from 'test.wmv': Metadata: > WMFSDKVersion : 9.00.00.2980 > WMFSDKNeeded : 0.0.0.0000 > IsVBR : 1 > VBR Peak : 351 > Buffer Average : 728 Duration: 00:00:05.59, start: 0.000000, bitrate: 574 kb/s > Stream #0:0(jpn): Audio: wmav2 (a[1][0][0] / 0x0161), 22050 Hz, 2 channels, s16, 32 kb/s > Stream #0:1(jpn): Video: wmv1 (WMV1 / 0x31564D57), yuv420p, 352x288, 520 kb/s, SAR 8:9 DAR 88:81, 29.97 tbr, 1k tbn, 1k tbc File > 'out2.flv' already exists. Overwrite ? [y/N] y w:352 h:288 > pixfmt:yuv420p tb:1/1000000 sar:8/9 sws_param: [image2 @ 0x551f880] decoding for stream 0 failed [image2 @ 0x551f880] Could not find codec parameters (Video: png) [movie @ 0x551f440] Failed to find stream info [movie @ 0x551f440] Failed to find any codec Error initializing filter 'movie' with args 'watermark_logo352.png' Error opening filters!When I use a
jpg, it works like a charm.I'm use ffmpeg v 0.10.4 on Debian 6 Squeeze. Any help would be much appreciated.
EDIT
The problem is simpler than i thought. If i use ffmpeg -i with any png image i get a similar error:
libavutil 51. 35.100 / 51. 35.100 libavcodec 53. 61.100 / 53. 61.100 libavformat 53. 32.100 / 53. 32.100 libavdevice 53. 4.100 / 53. 4.100 libavfilter 2. 61.100 / 2. 61.100 libswscale 2. 1.100 / 2. 1.100 libswresample 0. 6.100 / 0. 6.100 libpostproc 52. 0.100 / 52. 0.100 [image2 @ 0xc8b73a0] decoding for stream 0 failed [image2 @ 0xc8b73a0] Could not find codec parameters (Video: png) watermark.png: could not find codec parameters
