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• Capturing PCM audio data stream into file, and playing stream via ffmpeg, how ?

  11 avril 2015, par icarus74

  Would like to do following four things (separately), and need a bit of help understanding how to approach this,

  1. Dump audio data (from a serial-over-USB port), encoded as PCM, 16-bit, 8kHz, little-endian, into a file (plain binary data dump, not into any container format). Can this approach be used :

     $ cat /dev/ttyUSB0 > somefile.dat

  Can I do a ^C to close the file writing, while the dumping is in progress, as per the above command ?

  2. Stream audio data (same as above described kind), directly into ffmpeg for it to play out ? Like this :

     $ cat /dev/ttyUSB0 | ffmpeg

  or, do I have to specify the device port as a "-source" ? If so, I couldn’t figure out the format.

  Note that, I’ve tried this,

  $ cat /dev/urandom | aplay

  which works as expected, by playing out white-noise..., but trying the following doesn’t help :

  $ cat /dev/ttyUSB1 | aplay -f S16_LE

  Even though, opening /dev/ttyUSB1 using picocom @ 115200bps, 8-bit, no parity, I do see gibbrish, indicating presence of audio data, exactly when I expect.

  3. Use the audio data dumped into the file, use as a source in ffmpeg ? If so how, because so far I get the impression that ffmpeg can read a file in standard containers.

  4. Use pre-recorded audio captured in any format (perhaps .mp3 or .wav) to be streamed by ffmpeg, into /dev/ttyUSB0 device. Should I be using this as a "-sink" parameter, or pipe into it or redirect into it ? Also, is it possible that in 2 terminal windows, I use ffmpeg to capture and transmit audio data from/into same device /dev/ttyUSB0, simultaneously ?

  My knowledge of digital audio recording/processing formats, codecs is somewhat limited, so not sure if what I am trying to do qualifies as working with ’raw’ audio or not ?

  If ffmpeg is unable to do what I am hoping to achieve, could gstreamer be the solution ?

  PS> If anyone thinks that the answer could be improved, please feel free to suggest specific points. Would be happy to add any detail requested, provided I have the information.

• Specify timestamp in ffmpeg video segment command

  12 mai 2015, par Soumya

  I have a continuous RTSP stream coming from a camera over the network.
  I want to dump the stream but in video files of length 1 min each.

  I an using the following command

  ffmpeg -i "rtsp://user:pass@example.com"  -f mp4 -r 12 -s 640x480 -ar 44100 \
  
  -ac 1 -segment_time 60 -segment_format mp4 "out%03d.mp4"

  The name of the files being created are of the form out001.mp4, out002.mp4, etc.

  I want to include the timestamp (hour and minute) in the name of the file segments eg. 09-30.mp4, 09-31.mp4, etc.

  If it is mandatory to provide a serial number for the segment, is it possible to get something like 09-30-001.mp4, 09-31-002.mp4 ?

• Revision be6aeadaf4 : Try again to merge branch 'frame-parallel' into master branch. In frame paralle

  27 janvier 2015, par hkuang

  Changed Paths :
   Modify /test/decode_test_driver.cc

  
   Modify /test/test-data.mk

  
   Modify /test/test-data.sha1

  
   Modify /test/test.mk

  
   Modify /test/test_vector_test.cc

  
   Modify /test/test_vectors.cc

  
   Modify /test/vp9_encoder_parms_get_to_decoder.cc

  
   Add /test/vp9_frame_parallel_test.cc

  
   Modify /test/webm_video_source.h

  
   Modify /vp9/common/vp9_alloccommon.c

  
   Modify /vp9/common/vp9_alloccommon.h

  
   Modify /vp9/common/vp9_entropymode.c

  
   Modify /vp9/common/vp9_mvref_common.c

  
   Modify /vp9/common/vp9_mvref_common.h

  
   Modify /vp9/common/vp9_onyxc_int.h

  
   Modify /vp9/common/vp9_reconinter.c

  
   Modify /vp9/common/vp9_reconinter.h

  
   Modify /vp9/decoder/vp9_decodeframe.c

  
   Modify /vp9/decoder/vp9_decodeframe.h

  
   Modify /vp9/decoder/vp9_decodemv.c

  
   Modify /vp9/decoder/vp9_decodemv.h

  
   Modify /vp9/decoder/vp9_decoder.c

  
   Modify /vp9/decoder/vp9_decoder.h

  
   Add /vp9/decoder/vp9_dthread.c

  
   Add /vp9/decoder/vp9_dthread.h

  
   Modify /vp9/encoder/vp9_encoder.c

  
   Modify /vp9/encoder/vp9_encoder.h

  
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_pickmode.c

  
   Modify /vp9/encoder/vp9_rd.c

  
   Modify /vp9/encoder/vp9_rdopt.c

  
   Modify /vp9/vp9_cx_iface.c

  
   Modify /vp9/vp9_dx_iface.c

  
   Modify /vp9/vp9dx.mk

  
   Modify /vpx/vpx_frame_buffer.h

  
   Modify /webmdec.cc

  
   Modify /webmdec.h

  
  
  Try again to merge branch ’frame-parallel’ into master branch.

  In frame parallel decode, libvpx decoder decodes several frames on all
  cpus in parallel fashion. If not being flushed, it will only return frame
  when all the cpus are busy. If getting flushed, it will return all the
  frames in the decoder. Compare with current serial decode mode in which
  libvpx decoder is idle between decode calls, libvpx decoder is busy
  between decode calls.

  Current frame parallel decode will only speed up the decoding for frame
  parallel encoded videos. For non frame parallel encoded videos, frame
  parallel decode is slower than serial decode due to lack of loopfilter
  worker thread.

  There are still some known issues that need to be addressed. For example :
  decode frame parallel videos with segmentation enabled is not right sometimes.

  * frame-parallel :
  Add error handling for frame parallel decode and unit test for that.
  Fix a bug in frame parallel decode and add a unit test for that.
  Add two test vectors to test frame parallel decode.
  Add key frame seeking to webmdec and webm_video_source.
  Implement frame parallel decode for VP9.
  Increase the thread test range to cover 5, 6, 7, 8 threads.
  Fix a bug in adding frame parallel unit test.
  Add VP9 frame-parallel unit test.
  Manually pick "Make the api behavior conform to api spec." from master branch.
  Move vp9_dec_build_inter_predictors_* to decoder folder.
  Add segmentation map array for current and last frame segmentation.
  Include the right header for VP9 worker thread.
  Move vp9_thread.* to common.
  ctrl_get_reference does not need user_priv.
  Seperate the frame buffers from VP9 encoder/decoder structure.
  Revert "Revert "Revert "Revert 3 patches from Hangyu to get Chrome to
  build :"""
  Conflicts :
  test/codec_factory.h
  test/decode_test_driver.cc
  test/decode_test_driver.h
  test/invalid_file_test.cc
  test/test-data.sha1
  test/test.mk
  test/test_vectors.cc
  vp8/vp8_dx_iface.c
  vp9/common/vp9_alloccommon.c
  vp9/common/vp9_entropymode.c
  vp9/common/vp9_loopfilter_thread.c
  vp9/common/vp9_loopfilter_thread.h
  vp9/common/vp9_mvref_common.c
  vp9/common/vp9_onyxc_int.h
  vp9/common/vp9_reconinter.c
  vp9/decoder/vp9_decodeframe.c
  vp9/decoder/vp9_decodeframe.h
  vp9/decoder/vp9_decodemv.c
  vp9/decoder/vp9_decoder.c
  vp9/decoder/vp9_decoder.h
  vp9/encoder/vp9_encoder.c
  vp9/encoder/vp9_pickmode.c
  vp9/encoder/vp9_rdopt.c
  vp9/vp9_cx_iface.c
  vp9/vp9_dx_iface.c

  This reverts commit a18da9760a74d9ce6fb9f875706dc639c95402f5.

  Change-Id : I361442ffec1586d036ea2e0ee97ce4f077585f02