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• Create a video with audio only on one channel

  6 février 2018, par Jude Osborn

  I’m trying to create 5 videos that each play audio only in one channel. So, for example, one video only plays audio in the right front, another only in the back left, another only in the center, etc.

  The videos are currently stereo. Can I use ffmpeg to accomplish this ?

• Tools/Techniques for investigating video corruption — ffmpeg / libavcodec

  17 juillet 2013, par Gopherkhan

  In my current work I'm trying to encode some images to h264 video using the FFMPEG's C library. The resulting video plays fine in VLC, but has no preview image. The video can play in VLC and Mplayer on ubuntu, but won't play on Mac or PC (in fact, it causes a "VTDecoderXPCService quit unexpectedly" error on Mac).

  If I run the resulting file through FFMPEG using the command line, the resulting file has a preview image, and plays correctly everywhere.

  Apparently the file that I get out of the program is corrupt in some weird place, but I don't have any output during my compilation or run to indicate where. I can't share my code at the moment (work code isn't open source yet :-( ), but I have tried a number of things :

  1. Writing only header and trailer data (av_write_trailer) and no frames
  2. writing frames only minus the trailer (using avcodec_encode_video2 and av_write_frame)
  3. Adjusting our time_base and frame pts values to encode only one frame per second
  4. Removing all variable frame rate code
  5. Numerous other variants that I won't bother you with here

  In creating my project, I've also followed the following tutorials :

  • Dr. Anger's FFMPEG tutorial
  • FFmpeg's Own Tutorials
  • An older tutorial from FFmpeg

  And consulted the deprecated ffmpeg functions list

  And compiled FFMPEG on ubuntu according to the official doc

  And consulted numerous StackOverflow questions :

  • Raw H264 frames in mpegts container using libavcodec
  • How to encode Bitmaps into a video using MediaCodec ?
  • How to convert RGB from YUV420p for ffmpeg encoder ?
  • Encoding H.264 video using FFmpeg C API
  • ffmpeg : how to save h264 raw data as mp4 file

  But every run of the program runs into the exact same problem.

  My question is, is there anything obvious that causes a programmatic run of FFMpeg to differ from a console run (e.g., an incomplete finalization, some threading issues, etc.) ? Like some obvious reason that a console run could repair a corrupted file ? Or is there a decent tool/method for inspecting a video file and finding the point of corruption ?

• Converting .3gp file into mp4 file in android using ffmpeg

  8 août 2013, par user2171513

  I want to convert .3gp file into .mp4 file with resolution modified in Android using ffmpeg.
  I want to increase the resolution of the video from its standard resolution to 1920x1080.

  So far I have been successful in
  1) extracting .h264 video file from .3gp file and increase its resolution
  2) extracting .aac audio file from .3gp file.

  Now I want to combine them back into .mp4 file. The commands that I have used to extract this .h264 and .aac files are :

  ./ffmpeg -i 1.3gp -vbsf h264_mp4toannexb -s 1920x1080 1.h264
  
  ./ffmpeg -i 1.3gp -ab 160k -ac 2 -ar 48000 -vn -strict -2  1.aac

  The command that I have tried to merge them back is

  ./ffmpeg -i 1.h264 -i 1.aac -map 0:0 -map 1:0 -strict -2 1.mp4

  The 1.mp4 that gets generated at the end basically has audio only at few sync frames of video. (Thats what I feel , because the audio is present at specific intervals within the video)

  Can anyone please help in figuring out what am I missing here.

  EDIT :
  So basically I want to concat 4 different videos of 4 different resolution and type.

  1)

  ./ffmpeg -i 1.mp4 
  
  Video: h264 (High), yuv420p, 1920x1080, 16959 kb/s, 29.85 fps, 90k tbr, 90k tbn, 180k tbc
  
  Audio: aac, 48000 Hz, stereo, s16, 106 kb/s

  2)

  ffmpeg -i 2.mp4
  
  Video: h264 (Constrained Baseline), yuv420p, 640x480, 3102 kb/s, 29.99 fps, 90k tbr, 90k tbn, 180k tbc
  
  Audio: aac, 48000 Hz, stereo, s16, 93 kb/s

  3)

  ffmpeg -i 3.3gp
  
  Video: h263, yuv420p, 1408x1152 [PAR 12:11 DAR 4:3], 2920 kb/s, 15 fps, 15 tbr, 15360 tbn, 29.97 tbc
  
  Audio: amrnb, 8000 Hz, 1 channels, flt, 12 kb/s

  4)

  ffmpeg -i 4.3gp
  
  Video: h264 (High), yuv420p, 352x288 [PAR 12:11 DAR 4:3], 216 kb/s, 24 fps, 24 tbr, 24 tbn, 48 tbc
  
  Audio: aac, 44100 Hz, stereo, s16, 92 kb/s

  So I am converting them to mpegts using following commands

  ./ffmpeg -i 1.mp4 -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 1.ts
  
  ./ffmpeg -i 2.mp4 -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 2.ts
  
  ./ffmpeg -i 3.3gp -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 3.ts
  
  ./ffmpeg -i 4.3gp -c:v libx264 -vf scale=1920:1080 -r 60 -c:a aac -ar 48000 -b:a 160k -strict experimental -f mpegts 4.ts

  then concatenating the .ts files into f.ts and then creating a final .mp4 file from it using

   cat 1.ts 2.ts 3.ts 4.ts > f.ts
  
  ./ffmpeg -i f.ts -c copy -bsf:a aac_adtstoasc output.mp4

  But my f.ts also doesnt seem to play correctly in VLC on linux, it plays first 2 mp4's video + audio and it plays last .3gp's audio only.(Same for output.mp4 too) Could you please help me in figuring out what am I missing ?

  Thanks