Which audio file format gives smallest size for silent tracks?

Question

I want to make a bunch of silent audio files (of different lengths: A few seconds up to some minutes), just to but them into playlists and so on in order to have silent times in between.

I am wondering which audio file format to use which gives smallest file size while having exact silence.

Right now, I am using FLAC with 1kHz sampling rate, mono, 16 bits bit-depth. A 60 seconds silent file such is 723 bytes big. I created it with ReZound.

On my 60 second silent file, the output of mediainfo gives:

General
Complete name                            : silence-060s.flac
Format                                   : FLAC
Format/Info                              : Free Lossless Audio Codec
File size                                : 723 Bytes
Duration                                 : 1mn 0s
Overall bit rate mode                    : Variable
Overall bit rate                         : 96 bps

Audio
Format                                   : FLAC
Format/Info                              : Free Lossless Audio Codec
Duration                                 : 1mn 0s
Bit rate mode                            : Variable
Bit rate                                 : 85 bps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 1 000 Hz
Bit depth                                : 16 bits
Stream size                              : 637 Bytes (88%)
Writing library                          : libFLAC 1.3.1 (UTC 2014-11-25)

723 bytes filesize is already good, but comparing to the task -- just silence -- I would imagine you can encode it with just a few bytes for any lengths. You just would neet to specify the duration ... or have a bit depth of 0 bit and a sample rate of 1/duration.

But a 600s silent file is already 6.6 KiB big, the filesize scales approximately linear with the duration.

Is there any (at best free) audio file format which takes into account exact silence and can encode that in a feasible way? (OK, I might try MIDI or other sequencer-based formats, at least MIDI is not well supported on audio playback software on Linux and needs special software ...)

Answer 1

Just an idea (which needs further research): do you actually need the silence to be a file or could you just play dynamically created data? If the latter is the case, you could probably find a solution to call a program that creates a silent audio file in realtime and put that in your playlist. That way you would entirely get around the file size issues for your silence tracks. I don't know enough about Linux to know how to do this, but I am pretty sure this is possible somehow (maybe using named pipes running sox or Ffmpeg to create the silent track).