Answers.Body: <p>Your <code>ffmpeg</code> is outdated. Update and it will automatically insert some bitstream filters (at least aac_adtstoasc, hevc_mp4toannexb, h264_mp4toannexb). According to the <a href="https://ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc" rel="nofollow noreferrer">aac_adtstoasc documentation</a>:</p>
  
  <blockquote>
    <p>Please note that it is auto-inserted for MP4A-LATM and MOV/MP4 and
    related formats.</p>
  </blockquote>
  
  <p>It also seems to also work for Matroska. You can verify the behavior by adding <code>-loglevel debug</code> and viewing the output. Look for <code>Automatically inserted bitstream filter 'aac_adtstoasc'</code>.</p>
  
  <p>See the <a href="https://ffmpeg.org/download.html" rel="nofollow noreferrer">FFmpeg Download</a> page (<em>Get the Packages</em> section) for links to recent builds for Linux, macOS, and Windows. Get a build from the master branch: releases are essentially "frozen" branches derived from master; they are meant for distributors and those who need to stay within a particular API version. Releases receive less attention and get no new features so therefore they age quickly.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T16:05:45.840Z
Answers.Text: I'll give that a try. Honestly I should upgrade the entire distro on this machine. (Still running Ubuntu 14.04 on it)
Answers.UserDisplayName: Elder Geek
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T18:09:52.547Z
Answers.Text: @ElderGeek 18.04 LTS is 6 months away if you can wait.
Answers.UserDisplayName: llogan
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T18:13:54.630Z
Answers.Text: Oh yes, I can wait. I have other systems running 16.04 that I can use. I'm still running 14.04 on this system mainly so that I can support it (without the inherent delays of running a VM) :-)
Answers.UserDisplayName: Elder Geek
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T18:16:19.767Z
Answers.Text: So are you stating that with a recent version of ffmpeg (say 3.0 or above) I won't need the `-bsf:a aac_adtstoasc` switch?
Answers.UserDisplayName: Elder Geek
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T19:01:25.920Z
Answers.Text: @ElderGeek Yes, but I'm unsure what release, if any yet, have the autobsf behavior. Releases are just "frozen" branches from master and are intended for distributors and those who need to stick with a certain API version. Most general users should use a recent build from the master branch. You can add `-loglevel debug` and view the output. Look for `Automatically inserted bitstream filter 'aac_adtstoasc'`. The docs say, "Please note that it is auto-inserted for MP4A-LATM and MOV/MP4 and related formats", but it also seems to also work for Matroska.
Answers.UserDisplayName: llogan
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T19:26:32.047Z
Answers.Text: That's interesting information and certainly adds value to your answer. If I may be so bold to suggest incorporating it?
Answers.UserDisplayName: Elder Geek
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-23T19:53:58.377Z
Answers.Text: @ElderGeek Sure. Updated.
Answers.UserDisplayName: llogan
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-22T17:58:29.220Z
Answers.LastActivityDate: 2017-09-23T19:53:46.037Z
Answers.LastEditDate: 2017-09-23T19:53:46.037Z
Answers.UserDisplayName: llogan
Answers.Body: <p><code>ffmpeg</code> will happily rewrite the incorrect extradata for you if you simply copy the streams and utilize the bit stream filter aac_adtstoasc with the command <code>ffmpeg -i input.mp4 -bsf:a aac_adtstoasc -c:a copy -c:v copy output.mp4</code> the resulting file converts as expected.</p>
  
  <p>This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4 ADTS header and removes the ADTS header which appears was the root cause of the problem.</p>
  
  <p><code>mediainfo</code> reports the output file like this:</p>
  
  <pre><code>Format                                   : MPEG-4
  Format profile                           : Base Media
  Codec ID                                 : isom (isom/iso2/avc1/mp41)
  File size                                : 137 MiB
  Duration                                 : 25mn 31s
  Overall bit rate mode                    : Variable
  Overall bit rate                         : 750 Kbps
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  Writing application                      : Lavf56.40.101
  
  Video
  ID                                       : 1
  Format                                   : AVC
  Format/Info                              : Advanced Video Codec
  Format profile                           : Main@L3
  Format settings, CABAC                   : Yes
  Format settings, ReFrames                : 1 frame
  Format settings, GOP                     : M=1, N=50
  Codec ID                                 : avc1
  Codec ID/Info                            : Advanced Video Coding
  Duration                                 : 25mn 31s
  Duration_FirstFrame                      : 40ms
  Duration_LastFrame                       : 23ms
  Bit rate                                 : 650 Kbps
  Width                                    : 854 pixels
  Height                                   : 480 pixels
  Display aspect ratio                     : 16:9
  Original display aspect ratio            : 16:9
  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)                       : 0.063
  Stream size                              : 118 MiB (86%)
  Writing library                          : x264 core 148 r236 a01e339
  Encoding settings                        : cabac=1 / ref=1 / deblock=1:-1:-1 / analyse=0x1:0x111 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-1 / threads=2 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / stitchable=1 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=50 / keyint_min=5 / scenecut=0 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=650 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=850 / vbv_bufsize=850 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Audio
  ID                                       : 2
  Format                                   : AAC
  Format/Info                              : Advanced Audio Codec
  Format profile                           : LC
  Codec ID                                 : 40
  Duration                                 : 25mn 31s
  Bit rate mode                            : Variable
  Bit rate                                 : 96.0 Kbps
  Maximum bit rate                         : 217 Kbps
  Channel(s)                               : 2 channels
  Channel positions                        : Front: L R
  Sampling rate                            : 44.1 KHz
  Frame rate                               : 43.066 fps (1024 spf)
  Compression mode                         : Lossy
  Stream size                              : 17.6 MiB (13%)
  Default                                  : Yes
  Alternate group                          : 1
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  </code></pre>
  
  <p>And a diff of the reports shows the relevant changes made:</p>
  
  <pre><code>6c6
  &lt; File size                                : 138 MiB
  ---
  &gt; File size                                : 137 MiB
  9c9
  &lt; Overall bit rate                         : 755 Kbps
  ---
  &gt; Overall bit rate                         : 750 Kbps
  11a12
  &gt; Writing application                      : Lavf56.40.101
  24a26
  &gt; Duration_LastFrame                       : 23ms
  26,29c28,29
  &lt; Width                                    : 864 pixels
  &lt; Original width                           : 854 pixels
  &lt; Height                                   : 470 pixels
  &lt; Original height                          : 480 pixels
  ---
  &gt; Width                                    : 854 pixels
  &gt; Height                                   : 480 pixels
  30a31
  &gt; Original display aspect ratio            : 16:9
  37c38
  &lt; Bits/(Pixel*Frame)                       : 0.064
  ---
  &gt; Bits/(Pixel*Frame)                       : 0.063
  47a49
  &gt; Format profile                           : LC
  51c53,54
  &lt; Bit rate                                 : 98.5 Kbps
  ---
  &gt; Bit rate                                 : 96.0 Kbps
  &gt; Maximum bit rate                         : 217 Kbps
  52a56
  &gt; Channel positions                        : Front: L R
  56c60,62
  &lt; Stream size                              : 18.0 MiB (13%)
  ---
  &gt; Stream size                              : 17.6 MiB (13%)
  &gt; Default                                  : Yes
  &gt; Alternate group                          : 1
  </code></pre>
  
  <p>Source: <a href="https://ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc" rel="nofollow noreferrer">https://ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc</a></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-22T15:03:01.997Z
Answers.LastActivityDate: 2017-09-22T15:03:01.997Z
Answers.UserDisplayName: Elder Geek
Body: <p>I'm using ffmpeg version 2.8.11 to convert an AVC/AAC video to HEVC/AAC: with the command <code>ffmpeg -loglevel error -i input.mp4 -c:a copy -c:v libx265 -preset fast -x265-params crf=25 -vf scale=-8:ih output.mkv</code></p>
  
  <p>The command works as expected on other files, but this particular file throws:</p>
  
  <p><code>[matroska @ 0x88c2e0] Error parsing AAC extradata, unable to determine samplerate.
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument</code></p>
  
  <p>Source info from mediainfo:</p>
  
  <pre><code>Format                                   : MPEG-4
  Format profile                           : Base Media
  Codec ID                                 : isom (isom/iso2/avc1/mp41)
  File size                                : 138 MiB
  Duration                                 : 25mn 31s
  Overall bit rate mode                    : Variable
  Overall bit rate                         : 755 Kbps
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Video
  ID                                       : 1
  Format                                   : AVC
  Format/Info                              : Advanced Video Codec
  Format profile                           : Main@L3
  Format settings, CABAC                   : Yes
  Format settings, ReFrames                : 1 frame
  Format settings, GOP                     : M=1, N=50
  Codec ID                                 : avc1
  Codec ID/Info                            : Advanced Video Coding
  Duration                                 : 25mn 31s
  Duration_FirstFrame                      : 40ms
  Bit rate                                 : 650 Kbps
  Width                                    : 864 pixels
  Original width                           : 854 pixels
  Height                                   : 470 pixels
  Original height                          : 480 pixels
  Display aspect ratio                     : 16:9
  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)                       : 0.064
  Stream size                              : 118 MiB (86%)
  Writing library                          : x264 core 148 r236 a01e339
  Encoding settings                        : cabac=1 / ref=1 / deblock=1:-1:-1 / analyse=0x1:0x111 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-1 / threads=2 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / stitchable=1 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=50 / keyint_min=5 / scenecut=0 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=650 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=850 / vbv_bufsize=850 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Audio
  ID                                       : 2
  Format                                   : AAC
  Format/Info                              : Advanced Audio Codec
  Codec ID                                 : 40
  Duration                                 : 25mn 31s
  Bit rate mode                            : Variable
  Bit rate                                 : 98.5 Kbps
  Channel(s)                               : 2 channels
  Sampling rate                            : 44.1 KHz
  Frame rate                               : 43.066 fps (1024 spf)
  Compression mode                         : Lossy
  Stream size                              : 18.0 MiB (13%)
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  </code></pre>
  
  <p>I've tested playback of the source file which works as expected on both totem and mplayer. Based on the error I can only surmise that there's something off with the AAC stream description data. (extradata). My goal is to somehow repair/normalize this data so that I can successfully transcode it with HEVC encoder v.1.9</p>
  
Tags: <ffmpeg><audio>
Title: Error converting mp4 to matroska format
UserDisplayName: Elder Geek
ThreadText: # Error converting mp4 to matroska format
  
  (Asked by: username_0 on 2017-09-21)
  
  I'm using ffmpeg version 2.8.11 to convert an AVC/AAC video to HEVC/AAC: with the command `ffmpeg -loglevel error -i input.mp4 -c:a copy -c:v libx265 -preset fast -x265-params crf=25 -vf scale=-8:ih output.mkv`
  
  The command works as expected on other files, but this particular file throws:
  
  `[matroska @ 0x88c2e0] Error parsing AAC extradata, unable to determine samplerate.
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument`
  
  Source info from mediainfo:
  
  ```
  Format                                   : MPEG-4
  Format profile                           : Base Media
  Codec ID                                 : isom (isom/iso2/avc1/mp41)
  File size                                : 138 MiB
  Duration                                 : 25mn 31s
  Overall bit rate mode                    : Variable
  Overall bit rate                         : 755 Kbps
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Video
  ID                                       : 1
  Format                                   : AVC
  Format/Info                              : Advanced Video Codec
  Format profile                           : Main@L3
  Format settings, CABAC                   : Yes
  Format settings, ReFrames                : 1 frame
  Format settings, GOP                     : M=1, N=50
  Codec ID                                 : avc1
  Codec ID/Info                            : Advanced Video Coding
  Duration                                 : 25mn 31s
  Duration_FirstFrame                      : 40ms
  Bit rate                                 : 650 Kbps
  Width                                    : 864 pixels
  Original width                           : 854 pixels
  Height                                   : 470 pixels
  Original height                          : 480 pixels
  Display aspect ratio                     : 16:9
  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)                       : 0.064
  Stream size                              : 118 MiB (86%)
  Writing library                          : x264 core 148 r236 a01e339
  Encoding settings                        : cabac=1 / ref=1 / deblock=1:-1:-1 / analyse=0x1:0x111 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-1 / threads=2 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / stitchable=1 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=50 / keyint_min=5 / scenecut=0 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=650 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=850 / vbv_bufsize=850 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Audio
  ID                                       : 2
  Format                                   : AAC
  Format/Info                              : Advanced Audio Codec
  Codec ID                                 : 40
  Duration                                 : 25mn 31s
  Bit rate mode                            : Variable
  Bit rate                                 : 98.5 Kbps
  Channel(s)                               : 2 channels
  Sampling rate                            : 44.1 KHz
  Frame rate                               : 43.066 fps (1024 spf)
  Compression mode                         : Lossy
  Stream size                              : 18.0 MiB (13%)
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  ```
  
  I've tested playback of the source file which works as expected on both totem and mplayer. Based on the error I can only surmise that there's something off with the AAC stream description data. (extradata). My goal is to somehow repair/normalize this data so that I can successfully transcode it with HEVC encoder v.1.9
  
  **Tags:** ffmpeg, audio
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2017-09-22. Score: 4
  
  Your `ffmpeg` is outdated. Update and it will automatically insert some bitstream filters (at least aac\_adtstoasc, hevc\_mp4toannexb, h264\_mp4toannexb). According to the [aac\_adtstoasc documentation](https://ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc):
  
  > Please note that it is auto-inserted for MP4A-LATM and MOV/MP4 and
  > related formats.
  
  It also seems to also work for Matroska. You can verify the behavior by adding `-loglevel debug` and viewing the output. Look for `Automatically inserted bitstream filter 'aac_adtstoasc'`.
  
  See the [FFmpeg Download](https://ffmpeg.org/download.html) page (*Get the Packages* section) for links to recent builds for Linux, macOS, and Windows. Get a build from the master branch: releases are essentially "frozen" branches derived from master; they are meant for distributors and those who need to stay within a particular API version. Releases receive less attention and get no new features so therefore they age quickly.
  
  > **Comments:**
  > **username_0**: I'll give that a try. Honestly I should upgrade the entire distro on this machine. (Still running Ubuntu 14.04 on it)  
  > **username_1**: @username_0 18.04 LTS is 6 months away if you can wait.  
  > **username_0**: Oh yes, I can wait. I have other systems running 16.04 that I can use. I'm still running 14.04 on this system mainly so that I can support it (without the inherent delays of running a VM) :-)  
  > **username_0**: So are you stating that with a recent version of ffmpeg (say 3.0 or above) I won't need the `-bsf:a aac_adtstoasc` switch?  
  > **username_1**: @username_0 Yes, but I'm unsure what release, if any yet, have the autobsf behavior. Releases are just "frozen" branches from master and are intended for distributors and those who need to stick with a certain API version. Most general users should use a recent build from the master branch. You can add `-loglevel debug` and view the output. Look for `Automatically inserted bitstream filter 'aac_adtstoasc'`. The docs say, "Please note that it is auto-inserted for MP4A-LATM and MOV/MP4 and related formats", but it also seems to also work for Matroska.  
  > **username_0**: That's interesting information and certainly adds value to your answer. If I may be so bold to suggest incorporating it?  
  > **username_1**: @username_0 Sure. Updated.  
  
  ---
  
  ### Answer by username_0 on 2017-09-22. Score: 2
  
  `ffmpeg` will happily rewrite the incorrect extradata for you if you simply copy the streams and utilize the bit stream filter aac\_adtstoasc with the command `ffmpeg -i input.mp4 -bsf:a aac_adtstoasc -c:a copy -c:v copy output.mp4` the resulting file converts as expected.
  
  This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4 ADTS header and removes the ADTS header which appears was the root cause of the problem.
  
  `mediainfo` reports the output file like this:
  
  ```
  Format                                   : MPEG-4
  Format profile                           : Base Media
  Codec ID                                 : isom (isom/iso2/avc1/mp41)
  File size                                : 137 MiB
  Duration                                 : 25mn 31s
  Overall bit rate mode                    : Variable
  Overall bit rate                         : 750 Kbps
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  Writing application                      : Lavf56.40.101
  
  Video
  ID                                       : 1
  Format                                   : AVC
  Format/Info                              : Advanced Video Codec
  Format profile                           : Main@L3
  Format settings, CABAC                   : Yes
  Format settings, ReFrames                : 1 frame
  Format settings, GOP                     : M=1, N=50
  Codec ID                                 : avc1
  Codec ID/Info                            : Advanced Video Coding
  Duration                                 : 25mn 31s
  Duration_FirstFrame                      : 40ms
  Duration_LastFrame                       : 23ms
  Bit rate                                 : 650 Kbps
  Width                                    : 854 pixels
  Height                                   : 480 pixels
  Display aspect ratio                     : 16:9
  Original display aspect ratio            : 16:9
  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)                       : 0.063
  Stream size                              : 118 MiB (86%)
  Writing library                          : x264 core 148 r236 a01e339
  Encoding settings                        : cabac=1 / ref=1 / deblock=1:-1:-1 / analyse=0x1:0x111 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-1 / threads=2 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / stitchable=1 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=50 / keyint_min=5 / scenecut=0 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=650 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=850 / vbv_bufsize=850 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Audio
  ID                                       : 2
  Format                                   : AAC
  Format/Info                              : Advanced Audio Codec
  Format profile                           : LC
  Codec ID                                 : 40
  Duration                                 : 25mn 31s
  Bit rate mode                            : Variable
  Bit rate                                 : 96.0 Kbps
  Maximum bit rate                         : 217 Kbps
  Channel(s)                               : 2 channels
  Channel positions                        : Front: L R
  Sampling rate                            : 44.1 KHz
  Frame rate                               : 43.066 fps (1024 spf)
  Compression mode                         : Lossy
  Stream size                              : 17.6 MiB (13%)
  Default                                  : Yes
  Alternate group                          : 1
  Encoded date                             : UTC 1904-01-01 00:00:00
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  ```
  
  And a diff of the reports shows the relevant changes made:
  
  ```
  6c6
  < File size                                : 138 MiB
  ---
  > File size                                : 137 MiB
  9c9
  < Overall bit rate                         : 755 Kbps
  ---
  > Overall bit rate                         : 750 Kbps
  11a12
  > Writing application                      : Lavf56.40.101
  24a26
  > Duration_LastFrame                       : 23ms
  26,29c28,29
  < Width                                    : 864 pixels
  < Original width                           : 854 pixels
  < Height                                   : 470 pixels
  < Original height                          : 480 pixels
  ---
  > Width                                    : 854 pixels
  > Height                                   : 480 pixels
  30a31
  > Original display aspect ratio            : 16:9
  37c38
  < Bits/(Pixel*Frame)                       : 0.064
  ---
  > Bits/(Pixel*Frame)                       : 0.063
  47a49
  > Format profile                           : LC
  51c53,54
  < Bit rate                                 : 98.5 Kbps
  ---
  > Bit rate                                 : 96.0 Kbps
  > Maximum bit rate                         : 217 Kbps
  52a56
  > Channel positions                        : Front: L R
  56c60,62
  < Stream size                              : 18.0 MiB (13%)
  ---
  > Stream size                              : 17.6 MiB (13%)
  > Default                                  : Yes
  > Alternate group                          : 1
  
  ```
  
  Source: <https://ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc>
  
  
  ---
  
  