Newest 'ffmpeg' Questions - Stack Overflow
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iPhone ffmpeg dev using libav to decode from AMR to ACC codec
10 octobre 2011, par VictorTIt seems to be that, the AMR support of AudioQueue has been disappeared since iOS 4.3 was released. I can't use audio frame received from RSTP server with old way:
audioFormat.mFormatID = kAudioFormatAMR; int err = AudioQueueNewOutput(&audioFormat, MyAudioQueueOutputCallback, self, NULL, kCFRunLoopCommonModes, 0, &audioQueue);As a result I received an error in last string.
Maybe someone know how to decode AMR AVPacket into raw buffer and encode it with AAC or MP3 using LIBAV?
I've tried to use
avcodec_decode_audio3It works and I can get raw buffer but when I'm trying to encode it with
avcodec_encode_audioI get 0 as result
This is my method to encode buffer:
- (AVPacket) encodeRawFrame:(const short *) in_buffer withSize:(unsigned int) in_buf_byte_size { AVPacket res; AVCodec *codec; AVCodecContext *c= NULL; int count, out_size, outbuf_size, frame_byte_size; uint8_t *outbuf; avcodec_init(); avcodec_register_all(); printf("Audio encoding\n"); codec = avcodec_find_encoder(CODEC_ID_AAC); if (!codec) { fprintf(stderr, "codec not found\n"); return res; } c= avcodec_alloc_context(); c->bit_rate = 64000; c->sample_rate = 24000; c->channels = 2; if (avcodec_open(c, codec) < 0) { fprintf(stderr, "could not open codec\n"); } else { frame_byte_size=c->frame_size*2*2; count = in_buf_byte_size/frame_byte_size; fprintf(stderr, "Number of frames: %d\n", count); outbuf_size = AVCODEC_MAX_AUDIO_FRAME_SIZE; outbuf = (uint8_t*) malloc(outbuf_size); out_size = avcodec_encode_audio(c, outbuf, outbuf_size, &in_buffer[frame_byte_size*i]); if(out_size >= 0) { res.size = outbuf_size; res.data = malloc(outbuf_size); } free(outbuf); } avcodec_close(c); av_free(c); return res; }After encoding "out_size" is always 0 and result buffer is empty.
Thanks.
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saving H.264 encoded images with libavcodec
8 octobre 2011, par user846400I am getting H.264 images from an IP camera and want to save the encoded images (without decoding). I am using output-example.c from ffmpeg (libavformat/output-example.c) for this purpose. For Saving the raw H.264 image, I do the following:
AVPacket pkt; av_init_packet(&pkt); if (c->coded_frame->pts != AV_NOPTS_VALUE) pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base); if(c->coded_frame->key_frame) pkt.flags |= PKT_FLAG_KEY; pkt.stream_index= st->index; pkt.data= (uint8_t *)ulAddr;//video_outbuf; pkt.size= out_size; save_image(pkt.data, out_size);Where ulAddr is the address pointer to the image and out_size is the image size. Instead of saving the images to a media video file, I want to save the individual images. save_image function simply uses basic fopen and fwrite functions for saving the images. If I decode the frame and then save, everything works fine. But I have problem saving the encoded frames. The encoded frames are saved with a very small size and then they cannot be decoded. Is there anything wrong? I will really appreciate any help in this regard.
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FFMpeg generating screenshots drop frames
6 octobre 2011, par MorganI'm using FFMpeg to extract frames from a video file, and for most videos it works flawlessly. But certain videos it seems to have to seek to the position that I want to take the screenshot from, and drops all the frames on the way there taking quite a while if the position i'm generating a screenshot from is near the end of the video. Here is the command I'm using to extract my screenshot.
ffmpeg -ss 60 -i input.mkv -vframes 1 -f image2 -an -r 1/5 output.jpg
and the output I receive
ffmpeg version 0.8.3, Copyright (c) 2000-2011 the FFmpeg developers built on Sep 20 2011 00:46:47 with clang 2.1 (tags/Apple/clang-163.7.1) configuration: --prefix=/Users/Morgan/Downloads/installed/ffmpeg --extra-libs=/Users/Morgan/Downloads/installed/lib/libfaac.a --enable-gpl --extra-cflags=-I/Users/Morgan/Downloads/installed/include --disable-ffplay --disable-ffserver --disable-shared --disable-debug --extra-ldflags=-L/Users/Morgan/Downloads/installed/lib --enable-libmp3lame --enable-libfaac --enable-libx264 --enable-nonfree --cc=clang libavutil 51. 9. 1 / 51. 9. 1 libavcodec 53. 7. 0 / 53. 7. 0 libavformat 53. 4. 0 / 53. 4. 0 libavdevice 53. 1. 1 / 53. 1. 1 libavfilter 2. 23. 0 / 2. 23. 0 libswscale 2. 0. 0 / 2. 0. 0 libpostproc 51. 2. 0 / 51. 2. 0 [matroska,webm @ 0x7f9dd3007c00] Estimating duration from bitrate, this may be inaccurate Seems stream 0 codec frame rate differs from container frame rate: 47.95 (500000/10427) -> 23.98 (24000/1001) Input #0, matroska,webm, from 'input.mkv': Duration: 01:01:36.16, start: 0.000000, bitrate: 576 kb/s Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x720, PAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default) Metadata: title : Input Video Stream #0.1(eng): Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s (default) Metadata: title : English Dolby Digital 5.1 AC3 Stream #0.2(eng): Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s Metadata: title : Commentary Stream #0.3(eng): Subtitle: [0][0][0][0] / 0x0000 (default) Metadata: title : English Incompatible pixel format 'yuv420p' for codec 'mjpeg', auto-selecting format 'yuvj420p' [buffer @ 0x106c10c00] w:1280 h:720 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param: [buffersink @ 0x106c10e40] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out' [scale @ 0x106c11140] w:1280 h:720 fmt:yuv420p -> w:1280 h:720 fmt:yuvj420p flags:0x4 Output #0, image2, to 'output.jpg': Metadata: encoder : Lavf53.4.0 Stream #0.0(eng): Video: mjpeg, yuvj420p, 1280x720 [PAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 0.20 tbc (default) Metadata: title : Input Video Stream mapping: Stream #0.0 -> #0.0 Press [q] to stop, [?] for help frame= 0 fps= 0 q=0.0 Lsize= -0kB time=00:00:00.00 bitrate= 0.0kbits/s dup=0 drop=275 video:0kB audio:0kB global headers:0kB muxing overhead -inf% -
Can I force FFMPEG to insert keyframes every second ?
6 octobre 2011, par Kristian FrostI'm converting a bunch of videos to FLV with FFmpeg, and I've found the
-force_key_framesoption in the FFmpeg documentation.I want to insert a keyframe every second of the video, to enable smooth seeking. Is there any (easy) way to tell FFmpeg that I want a keyframe every second?
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Python/FFMPEG command line issues
5 octobre 2011, par 12hysI have a problem with running an FFMPEG command from within a Python script. When I run the following command from the terminal, I can stream video and audio from my attached webcam (Logitech C310) and output to file "out.avi" without any errors.
ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.aviWhen I run the same command in a Python script below,
def call_command(command): subprocess.Popen(command.split(' ')) call_command("ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi")it gives me the error:
Input #0, alsa, from 'default': Duration: N/A, start: 1317762562.695397, bitrate: N/A Stream #0.0: Audio: pcm_s16le, 44100 Hz, 1 channels, s16, 705 kb/s [video4linux2 @ 0x165eb10]Cannot find a proper format for codec_id 0, pix_fmt -1. /dev/video0: Input/output errorCould anyone shed some light on what could be going on here? I've tried using os.system() as well as subprocess.call() and it gives me the same errors. I'm not sure where to start on what could be going wrong here. I tried searching for the "video4linux2 Cannot find a proper format for codec_id 0, pix_fmt -1" error, but couldn't find anything consistent.
I've also tried putting the "ffmpeg -f..." command in a shell script "test.sh", and giving it executable permissions. I then open terminal, and run "./test.sh", and it works. When I try calling the command "./test.sh" from within my Python script, I'm left with the original error as before. This is the Python command I tried with the test.sh script:
subprocess.call(["./test.sh"])
