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• How to stream frames from ffmpeg to a process ?

  7 mars, par Vorac

  I would like to encrypt camera frames before transmitting. For that purpose the encrypting process needs to get the raw frames through some mode of IPC. I tried reading through the steaming API docs but got lost. This is an "what approach" question instead of a "working solution" one.

  


• How to keep compatibility when compiling ffmpeg with android ndk

  2 novembre 2015, par Fido Zhang

  I have successfully compiled ffmpeg as a static library for my project with android-platform 19 which specified in Application.xml as below :

  APP_PLATFORM := android-19

  I test my project on a device(4.4),it runs well. But it will crash on 4.0 devices.

  So I would like to changed the APP_PLATFORM to a lower version like :

  APP_PLATFORM := android-17

  But the ide comes out an error like this.

  libavcodec/ffv1enc.c:631: error: undefined reference to 'log2'

  And when I changed it to a more lower version :

  APP_PLATFORM := android-8

  More errors occured :

  libavcodec/ffv1enc.c:631: error: undefined reference to 'log2'
  
  libavutil/mem.c:94: error: undefined reference to 'posix_memalign'

  I know the log2 reference is undefined because of missing libm, but as far as I see Android will automatic link to libm when building.http://mobilepearls.com/labs/native-android-api/ndk/docs/STABLE-APIS.html

  So how can I keep compatibility when compiling ffmpeg in order to run my project well on lower version devices.

• How to set fractional values for `seg_duration` when using ffmpeg's dash muxer ?

  29 décembre 2019, par agconti

  I’m trying to set a fractional value for seg_duration when using ffmepg’s dash muxer like the docs suggest. When I switch between integer decimal values, I don’t get different results. How can I set a fractional value for seg_duration ?

  • E.g. Running my command with seg_duration equal to 1 produces the same minBufferTime as using 0.01.
  • In the source, seg_duration is represented as an int64_t so I don’t see how you can pass a fraction to it.

  Here’s an example ffmpeg command to reproduce :

  ffmpeg -loglevel verbose \
  
  -i $INGESTION_PATH \
  
  -seg_duration 0.01 \
  
  -use_template 1 \
  
  -use_timeline 0 \
  
  -f dash $OUTPUT_PATH

  Here’s the snippet from the docs on seg_duration :

  seg_duration duration

  Set the segment length in seconds (fractional value can be set). The value is treated as average segment duration when use_template is enabled and use_timeline is disabled and as minimum segment duration for all the other use cases.