January 2011 - ffmpeg-user - lists.ffmpeg.org

Frame/gop accurate video splitting (fps, gop, length known)
by abodera＠gmail.com 22 Dec '11

22 Dec '11

Hey there! A simple use case: 1) a sample mp4 file of 23.98 tbr, 264 + aac, 1:51.27 in length 2) the file (lotr trailer) encoded with: ./ffmpeg -i ./lordoftherings_h640_ml.mov -vcodec libx264 -g 50 ./lord.mp4 3) we want to split it in 3 parts: 30s, 10s and the rest of the stream Chunks we want to have: 1) ~30s (00:00:00 - 00:00:30) 2) ~10s (00:00:30 - 00:00:40) 3) ~71s (00:00:40 - 00:01:51) File info: Duration: 00:01:51.27, start: 0.000000, bitrate: 256 kb/s Stream #0.0(eng): Video: h264, yuv420p, 640x272, 192 kb/s, 47.90 fps, 23.98 tbr, 24k tbn, 47.95 tbc Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 58 kb/s The only tools right now are -vframes, -ss and -t. Frame-accurate seeking is missing/broken (?). Below is my approach. a) chunk 1 is 30s, so with 23.98 fps that gives 719.5 frames. b) Because it's gop 50 we round down to 700 frames = 29.1909925 seconds from start c) Chunk 1 extraction: "-vframes 699" d) Chunk 2 starts from frames 700 and ends in 10s = 239.8 frames ~ 250 frames (gop 50) e) Chunk 2 extraction: "-ss 29.1909925 -vframes 250" f) Chunk 3 starts at 40s = 959.2th frames (23.98 fps). Rounding down to 50 gives us 950th frame g) 950th frame is at aproximately 39.61635 sec. g) Chunk 3 extraction: "-ss 39.61635" Of course I wouldn't be bothering the community if it worked properly :-) The chunks are off by many seconds, lengths are off. Please assist - what am I doing wrong? Is there any more elegant way to do that? Also: a simpler case that I thought would "just work" - split the stream in two: ./ffmpeg -y -ss -t 30 -i ./lord.mp4 -vcodec copy -acodec copy lord-chunk1.mp4 ./ffmpeg -y -ss 00:00:30 -i ./lord.mp4 -vcodec copy -acodec copy lord-chunk2.mp4 It doesn't work! This will also end badly with two arbitrary length chunks with seek times that make little sense. How is it done properly? Thanks! Arthur. ps: FFmpeg version SVN-r20880 -- __ /.)\ +48 695 600 936 \(./ abodera at gmail.com

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XDCAM HD 35
by domich1＠gmail.com 20 Nov '11

20 Nov '11

Does anybody knows can I transcode material to XDCAM HD 35 format with mxf wrapper and what is the exact command. I' ve seen the example for XDCAM HD 422 50 Mbit on the ffmbc site. ffmpeg -i <input_file> -pix_fmt yuv422p -vcodec mpeg2video -flags +ildct+ilme -top 1 -dc 10 -flags2 +ivlc+non_linear_q -qmin 1 -lmin '1*QP2LAMBDA' -vtag xd5c -rc_max_vbv_use 1 -rc_min_vbv_use 1 -b 50000k -minrate 50000k -maxrate 50000k -bufsize 36408333 -bf 2 -aspect 16:9 -acodec pcm_s16be -f mov output.mov -newaudio Is there equivalent to that command for XDCAM HD 35Mbit. Thank you ! -- View this message in context: http://ffmpeg-users.933282.n4.nabble.com/XDCAM-HD-35-tp3009996p3009996.html Sent from the FFmpeg-users mailing list archive at Nabble.com.

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iPhone Matrix Rotation Info
by ben.knight＠f-i.com 27 Sep '11

27 Sep '11

Hi. I am using ffmpeg to encode videos both uploaded from the web and from iPhones. Currently, we are rotating the iPhone videos with another script. This has worked great so far however we just launched a mobile version of our site and now videos that have been rotated 90 degrees won?t play on the iPhone. The videos that are rotated 270 degrees work fine. I am wondering if there is a way to encode the file with ffmpeg so that it keeps the rotation matrix information from the iPhone so that if I try to play it again on the iPhone it works? Thanks *Ben*

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changing GOP size
by nandan.amar＠gmail.com 15 Sep '11

15 Sep '11

dear one, can we change the gop size of mpeg/h264 video while encoding using ffmpeg... if yes, please share the required option with ffmpeg.

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milliseconds to mpeg-ts pts/dts
by steuer＠unixsystems.de 07 Sep '11

07 Sep '11

guys, i try to create an mpegts file from H.264 and ACC raw frames that i receive from a network connection. I create AVPacket structures, set data, size, pts and dts etc. manually. For the stream that I receive, PTS and DTS seem to be equal, so I just calculate the packet pts and dts with incoming pts / 1000.0 * 90000.0 I do that for audio and video. Unfortunately that seems to be wrong as ffmpeg states "dts < pcr, TS is invalid" after a couple of seconds. I seems that the timestamps run out of sync with the internal pcr reference clock. What would be the correct way to calculate the pts and dts of the mpegts stream? Thanks alot for your help! Cheers, Heri

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Hint tracks support for MP4
by stas.oskin＠gmail.com 16 Aug '11

16 Aug '11

Hi. Any idea if FFMPEG supports / will be supporting adding hint tracks to MP4 files for RTSP streaming? Regards.

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Using video card chipset to encode.
by drgkill＠gmail.com 10 Aug '11

10 Aug '11

Dear FFmpeg team, Your soft is really great, I use it every day, but with the announcement of Badabom from Nvidia, I was asking myself if FFmpeg will handle the GPU to encode videos. They are announcing (Nvidia, AMD) 2x real time encoding rates (for more details, codec, video size, etc, see : http://www.youtube.com/watch?v=8C_Pj1Ep4nw) It's about 6 to 10 time faster than with my Xeon quad core. So I was wondering if FFmeg plan to implement that kind of code. Thanks by advance. Guillaume S.

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Piping trough Avisynth
by bouke＠editb.nl 25 Jun '11

25 Jun '11

Workin on PNG overlay trough Avisynth, and have MXF as a source and target file. Now i haven't found a proper MXF importer, so i'm rendering an (uncompressed) AVI inbetween file to feed Avisynth. This is kinda silly of course, there must be a way to pipe. But the question is, how? Bouke

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Unable to link my code with FFmpeg
by varundua007＠gmail.com 23 Jun '11

23 Jun '11

Hi All, I have build ffmpeg on windows using msys and mingw. I have written a small piece of code in C to convert a movie file to images. The file compiles well but it shows linking problem (I assume they are linking problems). I run my program using the following command gcc -Wall -I/local/include -L/local/lib test4.c when I use the -c option, test4.o file is created, but it gives problems when I remove the -c option. Please help me with this error C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0xea): undefined reference to `avpicture_get_size' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x12a): undefined reference to `avcodec_alloc_context' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x1b8): undefined reference to `avcodec_find_encoder' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x1e8): undefined reference to `avcodec_open' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x241): undefined reference to `avcodec_encode_video' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x2b1): undefined reference to `avcodec_close' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x2f0): undefined reference to `avpicture_get_size' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x330): undefined reference to `avcodec_alloc_context' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x3b8): undefined reference to `avcodec_find_encoder' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x3e8): undefined reference to `avcodec_open' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x441): undefined reference to `avcodec_encode_video' C:\Users\varund\AppData\Local\Temp\ccw1tHZ5.o:test4.c:(.text+0x4b1): undefined reference to `avcodec_close' ................. ............... collect2: ld returned 1 exit status Thanks Varun Dua

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Reading RTSP from Axis cameras via FFMPEG
by stas.oskin＠gmail.com 10 Jun '11

10 Jun '11

Hi. I'm trying to read video from Axis camera via ffmpeg and ffplay. The use link goes like this: rtsp://192.168.253.201:554/mpeg4/media.amp The video starts fine, but then immediately breaks to parts. ffmpeg/ffplay start to throw the following errors: [mpeg4 @ 0x1a350400]concealing 661 DC, 661 AC, 661 MV errors [mpeg4 @ 0x1a350400]slice end not reached but screenspace end (44419 left 6CC8BD, score= -262) [mpeg4 @ 0x1a350400]concealing 690 DC, 690 AC, 690 MV errors [mpeg4 @ 0x1a350400]slice end not reached but screenspace end (12453 left 7E1653, score= -263) [mpeg4 @ 0x1a350400]concealing 690 DC, 690 AC, 690 MV errors [mpeg4 @ 0x1a350400]1. marker bit missing in 3. esc [mpeg4 @ 0x1a350400]Error at MB: 206 [mpeg4 @ 0x1a350400]concealing 539 DC, 539 AC, 539 MV errors [mpeg4 @ 0x1a350400]slice end not reached but screenspace end (11108 left 7091E5, score= -268) [mpeg4 @ 0x1a350400]concealing 690 DC, 690 AC, 690 MV errors [mpeg4 @ 0x1a350400]I cbpy damaged at 18 9 [mpeg4 @ 0x1a350400]Error at MB: 297 [mpeg4 @ 0x1a350400]concealing 451 DC, 451 AC, 451 MV errors [mpeg4 @ 0x1a350400]slice end not reached but screenspace end (11107 left 6CF4B6, score= -275) [mpeg4 @ 0x1a350400]concealing 690 DC, 690 AC, 690 MV errors [mpeg4 @ 0x1a350400]slice end not reached but screenspace end (11110 left 7C5C0C, score= -279) [mpeg4 @ 0x1a350400]concealing 690 DC, 690 AC, 690 MV errors VLC, when connecting to same link, works just fine. Any idea what happens? Thanks!

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