[FFmpeg-trac] #10229(undetermined:new): Wrong data size for WAV (RIFF) format

[FFmpeg]

#10229: Wrong data size for WAV (RIFF) format
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             Reporter:  polochon     |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  pcm_u8 RIFF  |               Blocked By:
  WAV                                |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by polochon):

 Not sure to understand the point: what is the audacity bug you are
 talking?

 Regarding this file:
 - mediainfo says 1876 samples
 - according to you, Adobe audition says 1876 samples (if you count from 0
 to 1875, the result is still 1876).
 => both tools says the same thing.

 So why the data size encoded to the file by ffmpeg is 0x0753 => 1875?
 Basically, if you do a memcpy(dest,src,size) or a for(i=0; i<size; i++),
 you right size value is 1876, not 1875 or you will miss a sample.

 I've attached to the ticket a new file which is correctly encoded by
 ffmpeg: aston.wav (source) and astonEncoded.wav (converted by ffmpeg).
 This file is read correctly  by my robot firmware.

 mediainfo output:

 {{{
 Channel(s)                               : 1 channel
 Sampling rate                            : 8000
 Sampling rate                            : 8 000 Hz
 Samples count                            : 51972
 }}}


 output of converted file:

 {{{
 00000000  52 49 46 46 28 cb 00 00  57 41 56 45 66 6d 74 20
 |RIFF(...WAVEfmt |
 00000010  10 00 00 00 01 00 01 00  40 1f 00 00 40 1f 00 00
 |........ at ...@...|
 00000020  01 00 08 00 64 61 74 61  04 cb 00 00 83 83 83 83
 |....data........|
 00000030  81 81 81 81 80 7d 7e 7f  7e 80 80 81 81 80 7e 7e
 |.....}~.~.....~~|
 00000040  7e 7e 80 81 81 80 81 81  7f 7d 7e 7e 7d 7e 7e 7e
 |~~.......}~~}~~~|
 00000050
 }}}


 0xCB04 => 51972 samples, exactly the size computed by mediainfo.

 To resume:

 So, when ffmpeg encode the right size:
 - all the tools says are aligned on the same size value
 - I can compute the same value with the formula "file size - 44 bytes" (in
 my case without metadatas):
 - there is no issue on the thymio robot

 When ffmpeg miss 1 byte is the size field: thymio robot can't play the
 sound
 If I manually edit the size field to put the same value than mediainfo ->
 the robot can play the file

 Maybe it's an issue on certain conditions, maybe this is becauce the
 8000Hz data-rate, but I still highly suspect that ffmpeg miss 1 byte in
 the data size field sometimes

 Pol
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10229#comment:6>
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