FFprobe reports incorrect bit depth for some WavPack files

[ahthovaikied]

Generate a 24bit wave file (or use any existing one):

$ sox -n -b 24 a.wav synth 30 sine 1k

Encode it with wavpack, default lossless compression:

$ wavpack -q a.wav -o a.wv

Check it's still 24bits:

$ wvunpack -q -ss a.wv

file name:         a.wv
file size:         2700306 bytes
source:            24-bit ints at 48000 Hz
channels:          1 (mono)
duration:          0:00:30.00
modalities:        lossless
compression:       37.49%
ave bitrate:       720 kbps
encoder version:   4
file wrapper:      80 byte RIFF header

$ soxi a.wv

Input File     : 'a.wv'
Channels       : 1
Sample Rate    : 48000
Precision      : 24-bit
Duration       : 00:00:30.00 = 1440000 samples ~ 2250 CDDA sectors
File Size      : 2.70M
Bit Rate       : 720k
Sample Encoding: 24-bit WavPack

FFprobe report:

ffprobe -show_streams a.wv
ffprobe version N-66050-g098af26 Copyright (c) 2007-2014 the FFmpeg developers
  built on Sep  2 2014 22:46:46 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: 
  libavutil      54.  7.100 / 54.  7.100
  libavcodec     56.  1.100 / 56.  1.100
  libavformat    56.  3.100 / 56.  3.100
  libavdevice    56.  0.100 / 56.  0.100
  libavfilter     5.  0.103 /  5.  0.103
  libswscale      3.  0.100 /  3.  0.100
  libswresample   1.  1.100 /  1.  1.100
Input #0, wv, from 'a.wv':
  Duration: 00:00:30.00, start: 0.000000, bitrate: 720 kb/s
    Stream #0:0: Audio: wavpack, 48000 Hz, mono, '''s32p'''
[STREAM]
index=0
codec_name=wavpack
codec_long_name=WavPack
profile=unknown
codec_type=audio
codec_time_base=1/48000
codec_tag_string=[0][0][0][0]
codec_tag=0x0000
sample_fmt=s32p
sample_rate=48000
channels=1
channel_layout=mono
bits_per_sample=0
id=N/A
r_frame_rate=0/0
avg_frame_rate=0/0
time_base=1/48000
start_pts=0
start_time=0.000000
duration_ts=1440000
duration=30.000000
bit_rate=N/A
max_bit_rate=N/A
nb_frames=N/A
nb_read_frames=N/A
nb_read_packets=N/A
DISPOSITION:default=0
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
[/STREAM]

Problematic part is bits_per_sample=0 and sample_fmt=s32p.

[Carl Eugen Hoyos]

Patch sent.

[ahthovaikied]

Thanks.

Why differenciate bits_per_sample and bits_per_raw_sample though?

[Carl Eugen Hoyos]

Iirc, bits_per_sample is codec-specific and mostly meaningful for PCM and ADPCM codecs.

[ahthovaikied]

Replying to cehoyos:

Iirc, bits_per_sample is codec-specific and mostly meaningful for PCM and ADPCM codecs.

So what is the reliable, portable (across formats) way to get audio bits per sample ?

• bits_per_sample is 0 for most files
• bits_per_raw_sample seems correct after applying your patch for the 24bits example, but not always available (ie with a 16bit file)
• sample_fmt is unrelated ?

[Carl Eugen Hoyos]

Should be fixed in 42b4da75

Concerning your question, they are three different things, bits_per_sample is relevant for PCM codecs, bits_per_raw_sample is only relevant for codecs that actually compress and sample_fmt is FFmpeg's internal representation of the decoded data.

[cgbug]

Here is a WavPack sample that has a similar problem with Git-master:
​http://www.datafilehost.com/d/4859a6a1

[Carl Eugen Hoyos]

Replying to cgbug:

Here is a WavPack sample that has a similar problem with Git-master:
​http://www.datafilehost.com/d/4859a6a1

If you believe you found a bug in FFmpeg, please consider opening a ticket here, including your failing command line, the complete, uncut console output and a short explanation what went wrong.
If you have questions concerning the usage of FFmpeg, please post on the user mailing list.
Please avoid reopening old fixed tickets, unless you believe that the original issue was not fixed.
I don't know / understand what you want to report but it does not seem closely related to this ticket.

[cgbug]

The sample I posted gives bits_per_sample=0 and (as a result?) it also has a duration of 0.