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• FFmpeg only reading one channel

  29 août 2017, par AbstractDissonance

  Trying to read a stereo wav file and ffmpeg is only reading one channel. ffprobe returns 2 channels.

  I have used -ac 2 and then added -channel_layout stereo but all return 1 channel(or basically filling half the buffer I created).

  Basically the output size of ffmpeg is about half the wav file size.

  What I would like is for it to return every channel in

  Channel1_sample1, channel2_sample1, ..., ChannelN_sample1, channel1_sample2, etc...

  But, in reality, I’d rather just have it work with stereo ;) I’m giving it plenty large enough buffer to read to, so that isn’t the problem either.

  Here is the output

  ffprobe.exe -hide_banner -v quiet -print_format flat -show_streams -i temp.wav
  
  streams.stream.0.index=0
  
  streams.stream.0.codec_name="pcm_s16le"
  
  streams.stream.0.codec_long_name="PCM signed 16-bit little-endian"
  
  streams.stream.0.profile="unknown"
  
  streams.stream.0.codec_type="audio"
  
  streams.stream.0.codec_time_base="1/44100"
  
  streams.stream.0.codec_tag_string="[1][0][0][0]"
  
  streams.stream.0.codec_tag="0x0001"
  
  streams.stream.0.sample_fmt="s16"
  
  streams.stream.0.sample_rate="44100"
  
  streams.stream.0.channels=2
  
  streams.stream.0.channel_layout="unknown"
  
  streams.stream.0.bits_per_sample=16
  
  streams.stream.0.id="N/A"
  
  streams.stream.0.r_frame_rate="0/0"
  
  streams.stream.0.avg_frame_rate="0/0"
  
  streams.stream.0.time_base="1/44100"
  
  streams.stream.0.start_pts="N/A"
  
  streams.stream.0.start_time="N/A"
  
  streams.stream.0.duration_ts=14200200
  
  streams.stream.0.duration="322.000000"
  
  streams.stream.0.bit_rate="1411200"
  
  streams.stream.0.max_bit_rate="N/A"
  
  streams.stream.0.bits_per_raw_sample="N/A"
  
  streams.stream.0.nb_frames="N/A"
  
  streams.stream.0.nb_read_frames="N/A"
  
  streams.stream.0.nb_read_packets="N/A"
  
  streams.stream.0.disposition.default=0
  
  streams.stream.0.disposition.dub=0
  
  streams.stream.0.disposition.original=0
  
  streams.stream.0.disposition.comment=0
  
  streams.stream.0.disposition.lyrics=0
  
  streams.stream.0.disposition.karaoke=0
  
  streams.stream.0.disposition.forced=0
  
  streams.stream.0.disposition.hearing_impaired=0
  
  streams.stream.0.disposition.visual_impaired=0
  
  streams.stream.0.disposition.clean_effects=0
  
  streams.stream.0.disposition.attached_pic=0
  
  streams.stream.0.disposition.timed_thumbnails=0
  
  ffmpeg.exe -i temp.wav -loglevel quiet -f s16le -ac 2 -channel_layout stereo -

  temp.wav is just a standard stereo wav file.

• Bash Script to get info from ffprobe

  14 novembre 2016, par Alan

  I am trying to create a script to process videos, but I was hoping to get bit_rate, width, and height info from the incoming files so I could better tune the output. The script works when I do the files one at a time, but when I put it into a loop all of a sudden I don’t get any info.

  So this works :

  #!/bin/bash
  
  eval $(ffprobe -v quiet -show_format -of flat=s=_ -show_entries stream=height,width,nb_frames,duration,codec_name input.mp4);
  
  width=${streams_stream_0_width};
  
  height=${streams_stream_0_height};
  
  bitrate=$((${format_bit_rate}/1000));
  
  echo $width,$height,$bitrate;

  This doesn’t when executed from find ./ -type f -regex ".*\.\(mkv\|mp4\|wmv\|flv\|webm\|mov\|avi\)" -print0 | xargs -0 /root/newbatch.sh

  for i; do
  
  eval '$(ffprobe -v quiet -show_format -of flat=s=_ -show_entries stream=height,width,nb_frames,duration,codec_name $i)';
  
  width=${streams_stream_0_width};
  
  height=${streams_stream_0_height};
  
  bitrate=${format_bit_rate};
  
  kbitrate=$((bitrate/1000));
  
  echo $i,$width,$height,$kbitrate;
  
  
  
  done

  I also get an error with the math of bitrate in the loop, but even when I comment it out I still get no results. Since it works one at a time, I am assuming the problem is a bash scripting and nothing to do with ffmpeg / ffprobe.

  That being said, I can do this :

  echo $i,$width,$height,$bitrate;

  and get back

  ./file1.mkv,,,
  
  ./file2.mkv,,,
  
  ./file3.mkv,,,
  
  ./file4.mkv,,,

  So it does get some info back, but it loses the info from the eval statement.

• MP3 Audio requiring overlays at specific intervals to ensure I dont break copyright rules

  15 novembre 2012, par user1828008

  I have started a project as a DJ to record my online radio shows to mp3. The station I play on is licenced so I am not breaking any copyright rules there. I have had the idea to upload the recordings onto Youtube.

  Clearly that needed some form of adjustment to make a video over the top of the audio which I have achieved using ffmpeg so I have an mp4 file with a picture overlay for the duration of the audio. I did a quick test run to upload the video to Youtube and it tracked that I was playing copyrighted material. It was exactly right in its statement and yes as my own channel on youtube I am not licenced to do so. Either way I have spoke to the copyright owners and they have agreed it is fine.

  However in order to not have to do this every week if I overlay a 5 second 'jingle' every 4 minutes over the audio (fading down if possible) the main volume slightly to play the jingle and fade up after (once again if possible) then I am 100% in the clear. I could do this manually but would rather something I can script in bash to do it for me.

  I am using Centos 6.3 operating system and FFMPEG solved the merge of video and audio together, but I couldnt find anything to do a predefined audio overlay at specific intervals.

  I have looked at programs like Avisynth and Sox but dont believe from the documentation that they have anything that can do regular interval overlays during a single track. The closest thing I could find is on this post :

  Add multiple audio files to video at specific points using FFMPEG

  But it would be nice to do everything in a single sweep with ffmpeg of the audio file (video and audio overlay) if thats possible somehow or any better options that are out there ?

  If you need any more info from me then please let me know.
  Thanks