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• TV audio extracted using ffmeg does not work in iOS (but it works in the simulator)

  26 janvier 2014, par Genar

  I can process a TV signal (well I have a .ts video which comes from a TV channel), using ffmpeg but the audio cannot be understood in an iPhone/iPad. The most strange is that the audio (and video) works properly in the simulator (and also in an Android real device, but this is another point), but in a real iPhone/iPad device the video is OK but the audio sounds like a metallic box and nothing can be understood.

  I have created the ffmpeg libraries for iOS (I have tried the version 2.0.2 and also the version 2.1.3) using the information provided in the following link :

  Installing ffmpeg ios libraries armv7, armv7s, i386 and universal on Mac with 10.8

  The aforementioned link explains how to create the ffmpeg include folders and the universal libraries which I have included into my project (the libraries created are : libavcodec.a, libavdevice.a, libavfilter.a, libavformat.a, libavresample.a, libavutil.a, libswresample.a and libswscale.a).

  The sampling frequency used is 48000.

  The audio got from ffmpeg is then stored into a buffer and then "inserted" using OpenAL ; but, from the same TV content (the same .ts video file) the audio data which is generated from ffmpeg in an iPhone/iPad is totally different from the audio data generated from ffmpeg in the simulator (which can reproduce both the audio and video perfectly).

  Thanks in advance,

• concatenate mp4 videos with ffmpeg concat demuxer in android

  6 mai 2016, par Ara Badalyan

  I want to concatenate mp4 videos with ffmpeg, the problem is when I want to merge videos taken with Iphone and Android it throws problem

  " Non-monotonous DTS in output stream 0:1 ; previous : 150528, current : 139268 ; changing to 150529. This may result in incorrect timestamps in the output file."

  This is my code

  merge.txt

  file 'iphone.mp4'
  
  file 'android.mp4'

  ffmpeg command

  ffmpeg -f concat -i marge.txt -c copy -y merge.mp4

  If I can’t merge this videos how can i make them with same parameters (frame rate, bitrate...) and merge them ?

  P.S I use ffmpeg version 2.4.2 , because I can’t find android ffmpeg library higher then 2.4.2.

• FFmpeg playable MP4 segmented video from RTSP

  5 février 2021, par Michael Novotný

  I have problem with creating playable uncomplete MP4 file created from FFMPEG. In my case I have some infinite RTSP stream (h.264) from IP camera.
My target is record this stream to MP4 files for playback. If i use FFMPEG mp4 muxer, work correctly.

  


  /usr/bin/ffmpeg -progress pipe:5 -use_wallclock_as_timestamps 1 -analyzeduration 10000000 -probesize 10000000 -fflags +igndts -rtsp_transport tcp -hwaccel auto -loglevel warning -i rtsp://****:****@*******:****/ -y -an -vcodec copy -strict experimental -movflags frag_keyframe+empty_moov -f segment -segment_format mp4 -segment_format_options movflags=+faststart -segment_atclocktime 1 -reset_timestamps 1 -strftime 1 -segment_time 15 /Shinobi/videos/bWkwjTWdRt/Rm67cYyq50/test-%S.mp4


  


  FFMPEG will create one MP4 file which still increasing its size. If I try copy or simply open this (uncomplete, still increased ... of course :) ) file, it's correcly play. But it's still only one file ... still bigger and bigger. For long-term recording cam (few weeks) it's not good.
I want segment this stream to multiple smaller MP4 files (as you knows from another typical NVR systems). For example : segment for 30minutes.
I used "segment" muxer.

  


  /usr/bin/ffmpeg -progress pipe:5 -use_wallclock_as_timestamps 1 -analyzeduration 10000000 -probesize 10000000 -fflags +igndts -rtsp_transport tcp -hwaccel auto -loglevel warning -i rtsp://*****:****@*********:****/ -y -an -vcodec copy -strict -2 -movflags frag_keyframe+empty_moov -f mp4 -segment_atclocktime 1 -reset_timestamps 1 -strftime 1 -segment_list pipe:8 -segment_time 15 /Shinobi/videos/bWkwjTWdRt/Rm67cYyq50/test-%S.mp4


  


  It looks like work correctly. New file with defined mask is created every 30 minutes. If I try copy or simply open(and play) anyone "completed 30min segment file" it"s works correctly. Problem is with last file (more precisely : newest, still uncompleted last segment file) - it's not playable (moov atom not found).

  


  I Googled my problem many time with another keywords. I was try many my wonders. I readed FFMPEG documentation maybe 5times.

  


  Problem is with second passthroug which "segment muxer" do (which do -movflags +faststart .. for example). It's logicaly, second passthroug not be did in last(newest) file yet.

  


  Is there way to make it work ? If I want see time for 2-3 mins ago it's no possible wait up to 30minutes for "complete segment" ... and at the same time it is not possible to have a billion files with 2-3sec segments.
How did other NVR systems solve this ? Synology, Hikvision and more has in their file system recorded MP4 soubory which one of them is still uncompleted, still growing, but normaly PLAYABLE.

  


  A few last days I tried this with no success. I'am absolutely angry and sad. I hope that my text is understandable

  


  Thank you

  


  This options has no effect in my case (tried) :

  


  -movflags frag_keyframe+empty_moov

  


  -movflags faststart

  


  -movflags separate_moof

  


  -fragsize *** / -fragtime ***

  


  -strict -2 / -strict experimental