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• Batch Merge Large Number of Video Files by Pair

  16 février 2021, par dellyice

  I have a directory full of 1000+ short h.264 video clips that I'd like to batch merge via ffmpeg one pair at a time in Windows (eg, file1.mp4 is concatenated with file2.mp4, then file3.mp4 is concatenated with file4.mp4, etc, to ultimately produce half as many resultant videos, each containing two merged parent clips), and everything I've tried from fudging together scripts from other answers on the site has resulted in messes too embarrassing to mention.

  


  Each pair of videos is cut from a common source vid, so the concat demuxer should be fine for merging them. If it helps, each set of videos follows the naming scheme "filename"_1.mp4 and "filename"_2.mp4, so they're correctly paired alphabetically, and the _1 and _2 files can obviously be easily separated into different folders if need be.

  


  Sorry if any of this is terribly vague. If I had any productive work to show, I'd do so. Many thanks for any help.

  


• How to Buffer Audio Streams for an Android Internet Radio Application

  16 février 2014, par burakk

  We have a radio application that streams MP3 over HTTP using an instance of the MediaPlayer class. In devices running new Android versions (i.e, Note 3 running Android 4.3), the music plays for about half a second, and then waits (buffers ?) for up to 10 seconds, and plays again. I guess this unwanted behavior is due to the increased buffer size of the MediaPlayer in newer Android versions. Since there's no way to set the buffer size, there are few options left :

  • Stream Proxy
  • AudioTrack + MP3 Decoder
  • OpenSL

  I have read many posts about those, and concluded that the best way would be using AudioTrack with an MP3 decoder like FFMPEG. However, I am open to suggestions and any guidances since I do not have any knowledge about Android NDK, JNI and FFMPEG...

• FFMPEG : How to mix different types of image sequence inputs when creating multiple streams

  9 août 2021, par chutlies

  I am using a piece of software that generates a .txt files with rendered images. The list within that txt files is printed with the word 'file' at the beginning of the file path.

  


  Ex : file 'file:C :/Users/User/Desktop/test/Test.0001.png'

  


  I am attempting to input another image sequence as an overlay. Everything works fine if I just overlay, scale, and render. So this works fine :

  


  ffmpeg -hide_banner -y -f concat -safe 0 -i C:/test/input.txt -i "C:/test/BALL.%04d.png" -filter_complex "overlay[4K_in];[4K_in]scale=1920:1080[hdOut]" -map [hdOut] hd.mp4


  


  But when I start to split the stream to create different outputs it will only render the overlayed stream [1:v] and not the composited image.

  


  ffmpeg -hide_banner -y -f concat -safe 0 -i C:/test/input.txt -i "C:/test/BALL.%04d.png" -filter_complex "overlay,split=3[mp4HD_in][mxf720_in][mov4K_in];[mp4HD_in]scale=1920:1080[mp4HD_out];[mxf720_in]scale=1280:720[mxf720_out];[mov4K_in]scale=3840:2160[mov4K_out]" -crf 16 -vcodec libx264 -map [mp4HD_out] C:/test/hdMP4.mp4 -vcodec prores -map [mov4K_out] C:/test/MOV4K.mov -vcodec dnxhd -pix_fmt yuv422p -b:v 75M -map [mxf720_out] C:test/MXF720.mxf


  


  If I remove 'file' from the frames file path in the .txt file it works.

  


  Ex : file 'C :/Users/User/Desktop/test/Test.0001.png'

  


  Unfortunately, I am unable to change this as it's being generated and run within a piece of software. Are there any flags or something that I need to add to get around this ? Any other possible techniques beyond starting another &&ffmpeg call to generate the streams over the overlay ?

  


  I do get this in the logs :&#xA;[concat @ 0000024a0eacf280] DTS -230584300921369 < 0 out of order&#xA;DTS -230584300921369, next:40000 st:0 invalid dropping&#xA;PTS -230584300921369, next:40000 invalid dropping st:0&#xA;DTS -230584300921369, next:40000 st:0 invalid dropping&#xA;PTS -230584300921369, next:40000 invalid dropping st:0&#xA;DTS -230584300921369, next:40000 st:0 invalid dropping&#xA;PTS -230584300921369, next:40000 invalid dropping st:0&#xA;DTS -230584300921369, next:40000 st:0 invalid dropping&#xA;PTS -230584300921369, next:40000 invalid dropping st:0&#xA;[image2 @ 0000024a0eadd140] Thread message queue blocking ; consider raising the thread_queue_size option (current value : 8)

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