Bash: displaying selected output, do not print unnecessary output

Question

I don't know if it's possible: I'm using ffmpeg and I would like to reduce the output of a command. I have this result:

ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers
  built on Jun 17 2014 11:08:12 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-libvidstab --enable-libx265
  libavutil      52. 89.100 / 52. 89.100
  libavcodec     55. 67.100 / 55. 67.100
  libavformat    55. 43.100 / 55. 43.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  8.100 /  4.  8.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, hls,applehttp, from 'http://ftvodhdsecz-f.akamaihd.net/i/streaming-adaptatif_france-dom-tom/2014/S26/J7/104904507-20140629-,398,632,934,k.mp4.csmil/index_2_av.m3u8?null=':
  Duration: 00:51:05.07, start: 0.100667, bitrate: 0 kb/s
  Program 0 
    Metadata:
      variant_bitrate : 0
    Stream #0:0: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p, 704x396 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1: Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 67 kb/s
    Stream #0:2: Data: timed_id3 (ID3  / 0x20334449)
File '/media/path/video.mkv' already exists. Overwrite ? [y/N] y
[matroska @ 0x2958840] Error parsing AAC extradata, unable to determine samplerate.
Output #0, matroska, to '/media/path/video.mkv':
  Metadata:
    encoder         : Lavf55.43.100
    Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p, 704x396 [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 1k tbn, 90k tbc
    Stream #0:1: Audio: aac ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, 67 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[hls,applehttp @ 0x2864c20] Failed to open segment of playlist 0ate= 844.6kbits/s    
frame= 3000 fps=174 q=-1.0 Lsize=   12325kB time=00:02:00.00 bitrate= 841.4kbits/s

I just would like to have this 4 informations:

1) Duration: 00:51:05.07, start: 0.100667, bitrate: 0 kb/s
2)  File '/media/path/video.mkv' already exists. Overwrite ? [y/N] y
3)  Output #0, matroska, to '/media/path/video.mkv':
4)  frame= 3000 fps=174 q=-1.0 Lsize=   12325kB time=00:02:00.00 bitrate= 841.4kbits/s

I've tried the -v option, but the output is either -v info (this long output), or -v warning, or -v error. There's not what I would like to have. I've seen this question but the output is totally clear. Can I put an exception for specially string ? Thanks all

Edit: my line in my script is like that:

ffmpeg -i "${M3U2}" -vcodec copy -acodec copy "${Directory}/${PROG}_${ID}.mkv"

score 1 · Answer 1 · answered Jul 02 '14 at 07:27

1

You can redirect stderr to stdout and use grep to filter lines e.g.

ffmpeg -i "${M3U2}" -vcodec copy -acodec copy "${Directory}/${PROG}_${ID}.mkv" 2>&1 | grep -E -e '[[:blank:]]+Duration' -e '[[:blank:]]+File' -e '[[:blank:]]+Output' -e '[[:blank:]]+frame'

Or

ffmpeg -i "${M3U2}" -vcodec copy -acodec copy "${Directory}/${PROG}_${ID}.mkv" 2>&1 | egrep -e '^[[:blank:]]*(Duration|File|Output|frame)'

You should just have to make sure that your command won't be asking for input.

answered Jul 02 '14 at 07:27

konsolebox

72,135
12
99
105

1

or awk `awk '/^ Duration/ || /^File/ || /^Output/ || /^frame/'` – Jul 02 '14 at 07:28
@konsolebox: Thanks for your answer, I have just this line with your 2 lines: `Duration: 00:12:28.52, start: 0.100667, bitrate: 0 kb/s` – Guillaume Jul 02 '14 at 07:38
@Guillaume Like I said you should make sure that ffmpeg won't be asking for input. It could be possible that it's asking for a confirmation about overwriting the file. – konsolebox Jul 02 '14 at 07:41
@konsolebox: Ok, I see how it's work. I add the `-y` option to be sure. Thank you very much. However, the last line is dynamic, and do not display at all. – Guillaume Jul 02 '14 at 07:56
I've posted a [new question](http://stackoverflow.com/questions/24548159/bash-displaying-selected-dynamic-output) for the dynamic output. Thanks again – Guillaume Jul 03 '14 at 08:06

score 0 · Answer 2 · answered Jul 02 '14 at 07:34

0

I use

while read -d $'\n' -r line; do

  # dynamically filter line
  case line in:
   *what i want*)
   echo "hihih$line"
   ;;
  esac

done < <(program i want to run)

To dynamically filter output

answered Jul 02 '14 at 07:34

RedX

14,749
1
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Thanks, could you precise your code plz? I'm beginner in bash ! The konsolebox's code works, but not dynamic. With your code, i've this error: `Erreur de syntaxe près du symbole inattendu « in: »` (in french) – Guillaume Jul 02 '14 at 08:31

Bash: displaying selected output, do not print unnecessary output

Edit: my line in my script is like that:

2 Answers2

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