February 2018 - ffmpeg-user - lists.ffmpeg.org

use ffmpeg for iOS
by Yuan Le 07 Feb '18

07 Feb '18

Hello gus: I want to use ffmpeg for iOS,but I can`t find the docment aobut Ios .so please tell how to use it into my iOS project, I want to realize function of live telecast

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Error building ffmpeg with x265 support
by David Turner 07 Feb '18

07 Feb '18

I worked my through the tutorial on compiling ffmpeg with h.265 support found at https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu. The last thing it instructed me to do is PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure --prefix="$HOME/ffmpeg_build" --pkg-config-flags="--static" --extra-cflags="-I$HOME/ffmpeg_build/include" --extra-ldflags="-L$HOME/ffmpeg_build/lib" --extra-libs="-lpthread -lm" --bindir="$HOME/bin" --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree to which I got the following error: ERROR: x265 not found using pkg-config If you think configure made a mistake, make sure you are using the latest version from Git. If the latest version fails, report the problem to the ffmpeg-user(a)ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net. Include the log file "ffbuild/config.log" produced by configure as this will help solve the problem. Per the request above I am including the config.log file for your kindly review. Any thoughts? -David Turner"Linux user who knows just enough to be dangerous"

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ffplay cross-compilation
by Vladimir Kondenko 06 Feb '18

06 Feb '18

Hello. I'm trying to obtain an ffplay binary to use it in my Android app. But when I run my configure script, it says that sdl2 in not found although I cross-compiled it too and put its headers and library flags to --extra-cflags and --extraldflags. If I remove --enable-sdl2 ffplay simply wont appear in the list of the programs to be built. I managed to get it to compile on release/3.2 branch, but it throws an error regarding an undefined reference to 'main' in ether ffplay or libavutil.so files (depending on shared and/or static flags). Then I edited sdl2_cflags and sdl2_extralibs variables in the configure file on the master branch to point to my library, but it won't compile anyway. What am I doing wrong? My configure file has been changed this way: if enabled sdl2; then sdl2_cflags="-I/home/kondenko/Android/ffmpeg/ffmpeg/sdl2/include -D_REENTRANT" sdl2_extralibs="-L/home/kondenko/Android/ffmpeg/ffmpeg/sdl2/build/android/obj/local/armeabi-v7a -lSDL2" enable sdl2 fi And here's my script: make_or_die() { make -j $(nproc) || exit sudo make install || exit } ARCH=arm API=17 CPU=armv7 WORKING_DIR=~/Android/ffmpeg/ffmpeg NDK=~/Android/SDK/ndk TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi SYSROOT=$TOOLCHAIN/sysroot CROSS_PREFIX=$TOOLCHAIN/bin/arm-linux-androideabi- FFMPEG_PREFIX=$(pwd)/android/$CPU SDL=$(pwd)/sdl2 SDL_PREFIX=$SDL/build/android/obj/local/armeabi-v7a export PATH=$PATH:$TOOLCHAIN/bin:$TOOLCHAIN/include export CC="arm-linux-androideabi-clang" export CXX="arm-linux-androideabi-clang++" build_sdl2() { hg clone https://hg.libsdl.org/SDL $SDL cd $SDL sudo ./build-scripts/androidbuildlibs.sh cd $WORKING_DIR echo "SDL build folder: $SDL_PREFIX" } build_ffmpeg() { sudo make distclean sudo ./configure \ --target-os=android \ --arch=$ARCH \ --prefix=$FFMPEG_PREFIX \ --cross-prefix=$CROSS_PREFIX \ --enable-static \ --disable-ffprobe \ --disable-ffmpeg \ --disable-doc \ --disable-symver \ && make_or_die && header "Success! Your files are at $FFMPEG_PREFIX" \ || (echo \\n && tail ffbuild/config.log && exit) } build_sdl2 build_ffmpeg

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help please
by sarkis yol 06 Feb '18

06 Feb '18

hey what is the best way to hardcore subtitles into a movie while staying as close as possible to his original size and settings i tried this command: ffmpeg -i 1.mp4 -vf "subtitles=1.srt:force_style='FontName=Droid Naskh Shift Alt,Fontsize=21'" -c:a copy "output.mp4" but my 770mb movie goes to 1.3gb which is too much even though i tried another movie and went from 750 to 800 mb which is good but now allot of movies are getting x2 the size any help lease :)

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Continual reconnection attempts so long as video buffer has information
by Mr Arca9 05 Feb '18

05 Feb '18

running into an issue with HLS stability. Upon receiving a 403 from an m3u8 link, ffmpeg will only try to reconnect once and if it fails it will stop trying to reconnect. Is there a way to have ffmpeg reattempt to connect to stream X amount of times, regardless of responses or repeated failures?

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Fragmented mp4
by Er errechydy 05 Feb '18

05 Feb '18

Hi thanks for the great work, i hope you guys fine, I have a question related to fragmented mp4 that works on media source extension, i tried this code : " ffmpeg -i bunny.mp4 -movflags frag_keyframe+empty_moov+default_base_moof fragmented.mp4 " but when i try to play the video using media source extension and append other videos buffer ( made with the same command above ) it didn't work. My second question is what is the difference between " -f segment -segment_time 30 v%01d.mp4 " and " -ss 0 -t 30 v1.mp4 " they don't produce the same video , because when i use mp4fragment from Bento4 to turn the final video to fragmented mp4 , it worked with the second command but it didn't work for the first one, that means videos produced with " -f segment -segment_time 30 v%01d.mp4 " are different than from " -ss 0 -t 30 v1.mp4 ". thanks

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Hardware accelerated overlay
by Matthieu Pepin 05 Feb '18

05 Feb '18

Hi, I recently started to use hardware accelerated transcoding using ffmpeg and CUDA. It makes quite an improvement! The only thing I can't find for my use case is how to accelerate the overlay filter. Is there a CUDA version? Thanks! -- *Matthieu Pepin*

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RTP decoded video plays too fast
by Hooman Fazaeli 05 Feb '18

05 Feb '18

Hi, I am developing a SIP call recording app. To save conversations as playable media files, I has done the following: 1. Track SIP dialogs and save RTP media streams into custom .rtp files. The files have a header which contains stream encoding information (extracted form SDP payloads) followed by the RTP packets itself, saved consecutively and preceded w/ a 2 byte length field. 2. Developed a custom AVInputFormat. The format reads .rtp file header in its read_header method and sets stream codec and its parameters. It also creates RTPDemuxContext and RTPDynamicProtocolHandler instances. In its read_packet method, the format reads rtp packets and passes them to rtp demuxer. 3. To convert .rtp files to playable media, I use a simple command like below: > ffmpeg -i vp8-video.rtp vp8-video.flv The output contains the video as expected but it plays almost 2 times faster in VLC and widows media player. The problem exists w/ other output formats such as .avi or .mp4, too. Can anybody suggest what is going wrong? As RTP packets contain timing information, why ffmpeg decodes them in a faster rate? How I can fix the problem w/o using PTS filters? NOTE: The trans-coded audio streams do not have this problem and play w/ right speed.

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RTP decoded video plays too fast
by Hooman Fazaeli 05 Feb '18

05 Feb '18

I am developing a SIP call recording app. To save conversations as playable media files, I has done the following: 1. Track SIP dialogs and save RTP media streams into custom .rtp files. The files have a header which contains stream encoding information (extracted form SDP payloads) followed by the RTP packets itself, saved consecutively and preceded w/ a 2 byte length field. 2. Developed a custom AVInputFormat. The format reads .rtp file header in its read_header method and sets stream codec and its parameters. It also creates RTPDemuxContext and RTPDynamicProtocolHandler instances. In its read_packet method, the format reads rtp packets and passes them to rtp demuxer. 3. To convert .rtp files to playable media, I use a simple command like below: > ffmpeg -i vp8-video.rtp -o vp8-video.flv The output contains the video as expected but it plays almost 2 times faster in VLC and widows media player. The problem exists w/ other output formats such as .avi or .mp4, too. Can anybody suggest what is going wrong? As RTP packets contain timing information, why ffmpeg decodes them in a faster rate? How I can fix the problem w/o using PTS filters? NOTE: The trans-coded audio streams do not have this problem and play at correct rate. Pls. keep me CC'ed as I am not registered to the list. Thanks.

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command line help for merging two 360 streams
by Rudy Moore 04 Feb '18

04 Feb '18

tldr: I'd like to swap half of a video image from a first stream with an equal half of a video image from a second stream. I'd like to preserve the audio on each stream. Suggestions for how to do this with ffmpeg? I've got two Samsung Gear 360 (2016) and would like to make stereo stitched output from the two cameras. Each camera produces an MP4 video that is 3840x1920. Those videos have the output of two lenses mashed up against each other. Each separate lens is showing a circular image of about 190 degrees or so. And each half-image is 1920x1920. I normally use a program called "ActionDirector" to stitch these into a 360 image format. And in the end, I still will. The normal process is to stitch the two films, then open Premier Pro. I import them both into a project, align them based on the sound of snapping my fingers in the audio. Then I composite them one on the top of the image and one on the bottom. A 3D player can then play this back giving the left image to one eye and the right image to the other. The problem is that the camera placement is correct when looking one direction (left eye = left camera). But flip it around and now it's backwards (left eye = right camera). So I need to swap that 1920x1920 square from one video stream into the other and vice versa, ideally with no encoding loss. Suggestions on how to do that? For a quick hat trick, how about doing the steps that I'm currently doing on premier pro? That is, after the sitching in ActionDirector, how could I merge the two videos into a 360 video, complete with aligning the start times of the videos? Thanks for your suggestions!! Rudy

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