August 2014 - ffmpeg-user - lists.ffmpeg.org

Syncing clips based on audio waveform?
by Arthur Wait 05 Oct '17

05 Oct '17

Hi all, This is coming from out of left field I imagine, but I'm wondering if anyone knows of a filter (or chain of filters) which would allow me to align/sync two video clips based on matches in their audio waveforms. I'm shooting events with multiple cameras and would like to either trim the clips to a precise, matching starting frame or generate a metadata "offset" marker indicating how far off one clip is from the other in time. Then I can trim the clips to match. Is this possible in ffmpeg (or anywhere else for that matter!)? Thanks very much! Art

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could not find codec parameters for stream 0 unspecified size
by Ashish Lal 09 Aug '17

09 Aug '17

I am trying to convert a live rtsp stream (H264 + MPEG2 TS ) into MP4 using ffmpeg. I am getting an error "could not find codec parameters for stream 0 unspecified size". Any help in fixing this is appreciated. ffmpeg -rtsp_transport tcp -i rtsp://AA.BB.CC.DD:5555/mpeg2TransportStreamFr omUDPSourceTest -analyzeduration 999999999 -probesize 99999999 -vcodec libx264 -s 176x144 -b:v 256k -f mp4 -movflags frag_keyframe+empty_moov op.mp4 ffmpeg version 2.2.2 Copyright (c) 2000-2014 the FFmpeg developers built on May 27 2014 09:12:51 with gcc 4.7 (Debian 4.7.2-5) configuration: --enable-libx264 --enable-encoder=libx264 --enable-libvpx --pre fix=/home/ashish/ffmpeg-2.2.2/mybuild --enable-gpl --enable-debug --disable-stri pping --disable-optimizations --enable-memalign-hack libavutil 52. 66.100 / 52. 66.100 libavcodec 55. 52.102 / 55. 52.102 libavformat 55. 33.100 / 55. 33.100 libavdevice 55. 10.100 / 55. 10.100 libavfilter 4. 2.100 / 4. 2.100 libswscale 2. 5.102 / 2. 5.102 libswresample 0. 18.100 / 0. 18.100 libpostproc 52. 3.100 / 52. 3.100 [NULL @ 0x235cd60] non-existing PPS 0 referenced [h264 @ 0x235cd60] non-existing PPS 0 referenced [h264 @ 0x235cd60] decode_slice_header error [h264 @ 0x235cd60] no frame! [h264 @ 0x235cd60] non-existing PPS 0 referenced ......... ......... Last message repeated 1 times [h264 @ 0x235cd60] decode_slice_header error [h264 @ 0x235cd60] no frame! [h264 @ 0x235cd60] non-existing PPS 0 referenced [rtsp @ 0x232fc40] decoding for stream 0 failed [rtsp @ 0x232fc40] Could not find codec parameters for stream 0 (Video: h264 ([2 7][0][0][0] / 0x001B)): unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options rtsp://AA.BB.CC.DD:5555/mpeg2TransportStreamFromUDPSourceTest: could not find codec parameters Conversion failed! Regards Ashish

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Compiling FFMPEG with ffplay support
by Stas Oskin 14 Jun '17

14 Jun '17

Hi. Did the compilation parameters changed in recent FFMPEG version? Configuring the FFMPEG like this: ./configure --prefix=/usr --enable-pthreads Does not produce ffplay anymore. I tried to add --enable-ffplay, without any result. Any idea what I'm missing? Thanks.

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How do I encode DVB Subtitles?
by Wagner Patriota 02 May '17

02 May '17

*QUESTION 1:* How do I add a STR file to a MPEG-TS file with the "DVB subtitle codec"? If so, could you give me a sample command line? Thank. I am trying: ffmpeg -i video.ts *-i subtitle.srt* -vcodec copy -acodec copy *-scodec dvbsub* output.ts The stream is created because I can see it with MediaInfo, but the subtitles don't appear! *QUESTION 2:* How do I use the command *slang*? I try to use it, but ffmpeg says the command doesn't exist. Thank you.

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How to use global_header, fflags, rtpflags parameter.
by Ly Tran Cong 06 Dec '16

06 Dec '16

Hello, Can anyone tell me how to use flags +global_header, fflags +latm, rtpflags +latm Which parameter using with video encode and which parameter using with audio encode. Thanks -- Regards, Tran Ly Vega Corporation 98 Hoang Quoc Viet Str, Hanoi, Vietnam Tel: 84 4 755 4190 Fax: 84 4 755 4190 Mobile: 84 91 487 1115 www.vega.com.vn; www.clip.vn; www.chacha.vn; www.ringring.vn

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Flip in sws_scale
by romulo.fernandes＠gmail.com 11 Mar '16

11 Mar '16

Hello, I'm using libswscale to scale and convert pixel format from frames that I capture from the screen. In my windows build the frames that I capture are in DIB format. I'm using FFMPEG SVN rev 16437. Calling sws_scale normally I get the image correctly, except that it's vertically flipped. If I change the srcSliceY from 0 to srcHeight and srcSliceH from srcHeight to 0, I get a grey image (with correct dimensions). If I keep the srcSliceY in 0 and change srcSliceH from srcHeight to -srcHeight, I also get that grey image. Is there a way to make sws_scale flip the image for me ?

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Howto compile ffplay.c in seperate directory with my own svn-version of ffmpeg
by tps＠netmaster.dk 24 Feb '16

24 Feb '16

Dear All I have compiled svn-version of ffmpeg. I only do configure and make. I do not do make install because I don't want this svn-version of ffmpeg to overwrite the 'official' Ubuntu version of ffpeg that is also on the host. Now I want to compile my own version of ffplay.c so I create a directory ffplay at the same level as the svn ffmpeg-directory. I copy ffplay.c from ffmpeg to ffplay. Now what gcc options should I use to compile ffplay.c? I tried with this but got tons of errors: gcc -o ffplay ffplay.c -I../ffmpeg -L../ffmpeg/libavcodec -L../ffmpeg/libavformt -L../ffmpeg/libswscale -L../ffmpeg/libavutil -lavcodec -lavformat -lswscale -lavutil -lmp3lame -lx264 `sdl-config --cflags --libs` I note that when I do the make in the svn ffmpeg-directory there are a lot of options on the gcc command. I hardly know any of the options. Thanks in advance

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a -vf for broadcast safe
by Jim Shupert 30 Dec '15

30 Dec '15

I was wondering if there is a means to ensure that a file is transcoded as 'broadcast safe' input a unCompressed yuv avi and get a second Uncompressed yuv avi or mov and it would be 'broadcast safe'. I wish for the functionality of the broadcast safe effect available withing final cut 6. I do not find anything in the documentation. I wonder if Hald CLUT would be of any utility. thanks jim s

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timestamp calculation
by Chau Pham 25 Jun '15

25 Jun '15

Hi Everybody, Suppose that I know AVPacket element: pts, dts, duration How could I calculate the timestamp (hh:mm:ss:MMM)? Thank You,Chau Pham.

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Numerical histogram output for checking typical broadcast ranges (16-235)
by Christoph Gerstbauer 18 May '15

18 May '15

Hello, I am very new in using the histogram filter. (http://ffmpeg.org/ffmpeg-filters.html#histogram) Is it possible to dump the video level values from which the histogram graph is drawn into numeric values (textfile dump) to check if a video has levels inside the broadcast ranges (16-235/94-940)? bg Christoph

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