combing two .mp4 files using MP4Box makes only the first part of the video play audio, the second one doesn't.

shirish शिरीष shirishag75 at gmail.com
Tue Sep 18 19:01:22 UTC 2012


Hi all,
Dunno if it's a bug or not.

Hi all,
 I was looking for an mp4 merge tool and came across this. I used the
small tutorial given at
http://www.thetechrepo.com/main-articles/530-combine-mp4m4v-files-in-linuxubuntu

For seeing whether it works I combined two files which are similar at
least on the technical parameters :-

$ mediainfo b1.mp4
General
Complete name                            : b1.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42
File size                                : 28.5 MiB
Duration                                 : 9mn 51s
Overall bit rate mode                    : Variable
Overall bit rate                         : 405 Kbps
Encoded date                             : UTC 2011-01-03 14:48:08
Tagged date                              : UTC 2011-01-03 14:48:08
gsst                                     : 0
gstd                                     : 591783
gssd                                     : BADC23401HH1347937888871802
gshh                                     :
o-o---preferred---bom03s03---v16---lscache2.c.youtube.com

Video
ID                                       : 2
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline at L2.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Format settings, GOP                     : M=1, N=30
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 9mn 51s
Bit rate                                 : 353 Kbps
Maximum bit rate                         : 687 Kbps
Width                                    : 400 pixels
Height                                   : 326 pixels
Display aspect ratio                     : 1.227
Frame rate mode                          : Constant
Frame rate                               : 25.000 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.108
Stream size                              : 24.8 MiB (87%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:48:09
Tagged date                              : UTC 2011-01-03 14:48:09

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 9mn 51s
Bit rate mode                            : Variable
Bit rate                                 : 48.0 Kbps
Maximum bit rate                         : 57.1 Kbps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 3.50 MiB (12%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:48:08
Tagged date                              : UTC 2011-01-03 14:48:09


$ mediainfo b2.mp4
General
Complete name                            : b2.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42
File size                                : 34.8 MiB
Duration                                 : 12mn 0s
Overall bit rate mode                    : Variable
Overall bit rate                         : 404 Kbps
Encoded date                             : UTC 2011-01-03 14:57:13
Tagged date                              : UTC 2011-01-03 14:57:13
gsst                                     : 0
gstd                                     : 721396
gssd                                     : BADC23464MH1347938738207834
gshh                                     :
o-o---preferred---bom04s04---v14---lscache7.c.youtube.com

Video
ID                                       : 2
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline at L2.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Format settings, GOP                     : M=1, N=30
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 12mn 0s
Bit rate                                 : 352 Kbps
Maximum bit rate                         : 847 Kbps
Width                                    : 400 pixels
Height                                   : 326 pixels
Display aspect ratio                     : 1.227
Frame rate mode                          : Constant
Frame rate                               : 25.000 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.108
Stream size                              : 30.3 MiB (87%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:57:14
Tagged date                              : UTC 2011-01-03 14:57:14

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 12mn 0s
Bit rate mode                            : Variable
Bit rate                                 : 48.0 Kbps
Maximum bit rate                         : 59.0 Kbps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 4.26 MiB (12%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:57:13
Tagged date                              : UTC 2011-01-03 14:57:14


These I then decided to merge using the tutorial as a guide :-

$ MP4Box -cat b1.mp4 -cat b2.mp4 -new bmiddle.mp4
Appending file b1.mp4
No suitable destination track found - creating new one (type soun)
No suitable destination track found - creating new one (type vide)
Appending file b2.mp4
No suitable destination track found - creating new one (type soun)
Saving bmiddle.mp4: 0.500 secs Interleaving
[/code]

The end result bmiddle.mp4 plays but the audio in the second part does
not play.

Doing an inspection using mediainfo showed me this :-

$ mediainfo bmiddle.mp4
General
Complete name                            : bmiddle.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom
File size                                : 63.3 MiB
Duration                                 : 21mn 52s
Overall bit rate mode                    : Variable
Overall bit rate                         : 405 Kbps
Encoded date                             : UTC 2012-09-18 04:34:29
Tagged date                              : UTC 2012-09-18 04:34:29

Video
ID                                       : 2
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline at L2.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Format settings, GOP                     : M=1, N=30
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 21mn 52s
Bit rate                                 : 352 Kbps
Maximum bit rate                         : 687 Kbps
Width                                    : 400 pixels
Height                                   : 326 pixels
Display aspect ratio                     : 1.227
Frame rate mode                          : Constant
Frame rate                               : 25.000 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.108
Stream size                              : 55.1 MiB (87%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:48:09
Tagged date                              : UTC 2012-09-18 04:34:29

Audio #1
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 9mn 51s
Bit rate mode                            : Variable
Bit rate                                 : 48.0 Kbps
Maximum bit rate                         : 57.1 Kbps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 3.50 MiB (6%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:48:08
Tagged date                              : UTC 2012-09-18 04:34:29

Audio #2
ID                                       : 3
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 12mn 0s
Bit rate mode                            : Variable
Bit rate                                 : 48.0 Kbps
Maximum bit rate                         : 59.0 Kbps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 4.26 MiB (7%)
Title                                    : (C) 2007 Google Inc. v08.13.2007.
Encoded date                             : UTC 2011-01-03 14:57:13
Tagged date                              : UTC 2012-09-18 04:34:29

Why are there two Audio tracks given Audio #1 and Audio #2 ?

Did I do something wrong ? If yes, then what ? Trying to figure how
the tool works.

Looking forward for answers.
-- 
          Regards,
          Shirish Agarwal  शिरीष अग्रवाल
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