How to keep/force aspect ratio using ffmpeg

Question

I would like to remove pt-br audio and convert english DTS to AC3 and I'm using this command:

ffmpeg -i input.mkv -c:v copy -c:s copy -c:a ac3 -ac 2 -map 0:0 -map 0:2 -map 0:3 -aspect 16:9 test.mkv

ffmpeg version N-63968-g73d820e Copyright (c) 2000-2014 the FFmpeg developers
  built on Jun 15 2014 00:52:21 with gcc 4.8.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
  libavutil      52. 89.100 / 52. 89.100
  libavcodec     55. 66.101 / 55. 66.101
  libavformat    55. 43.100 / 55. 43.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  8.100 /  4.  8.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
[matroska,webm @ 0000000002c480c0] Could not find codec parameters for stream 3 (Subtitle: hdmv_pgs_subtitle): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, matroska,webm, from 'input.mkv':
  Metadata:
    encoder         : libebml v1.3.0 + libmatroska v1.4.0
    creation_time   : 2013-09-16 21:13:05
  Duration: 01:22:52.47, start: 0.000000, bitrate: 9307 kb/s
    Chapter #0.0: start 0.000000, end 137.846000
    Metadata:
      title           : 00:00:00.000
    Chapter #0.1: start 137.846000, end 227.185000
    Metadata:
      title           : 00:02:17.846
    Chapter #0.2: start 227.185000, end 351.643000
    Metadata:
      title           : 00:03:47.185
    Chapter #0.3: start 351.643000, end 536.035000
    Metadata:
      title           : 00:05:51.643
    Chapter #0.4: start 536.035000, end 648.982000
    Metadata:
      title           : 00:08:56.035
    Chapter #0.5: start 648.982000, end 901.359000
    Metadata:
      title           : 00:10:48.982
    Chapter #0.6: start 901.359000, end 1144.685000
    Metadata:
      title           : 00:15:01.359
    Chapter #0.7: start 1144.685000, end 1338.462000
    Metadata:
      title           : 00:19:04.685
    Chapter #0.8: start 1338.462000, end 1515.723000
    Metadata:
      title           : 00:22:18.462
    Chapter #0.9: start 1515.723000, end 1746.244000
    Metadata:
      title           : 00:25:15.723
    Chapter #0.10: start 1746.244000, end 1976.057000
    Metadata:
      title           : 00:29:06.244
    Chapter #0.11: start 1976.057000, end 2061.476000
    Metadata:
      title           : 00:32:56.057
    Chapter #0.12: start 2061.476000, end 2329.160000
    Metadata:
      title           : 00:34:21.476
    Chapter #0.13: start 2329.160000, end 2400.690000
    Metadata:
      title           : 00:38:49.160
    Chapter #0.14: start 2400.690000, end 2498.413000
    Chapter #0.15: start 2498.413000, end 2742.615000
    Metadata:
      title           : 00:41:38.413
    Chapter #0.16: start 2742.615000, end 3057.054000
    Metadata:
      title           : 00:45:42.615
    Chapter #0.17: start 3057.054000, end 3142.556000
    Metadata:
      title           : 00:50:57.054
    Chapter #0.18: start 3142.556000, end 3441.772000
    Metadata:
      title           : 00:52:22.556
    Chapter #0.19: start 3441.772000, end 3575.947000
    Metadata:
      title           : 00:57:21.772
    Chapter #0.20: start 3575.947000, end 3749.204000
    Metadata:
      title           : 00:59:35.947
    Chapter #0.21: start 3749.204000, end 3945.650000
    Metadata:
      title           : 01:02:29.204
    Chapter #0.22: start 3945.650000, end 4204.742000
    Metadata:
      title           : 01:05:45.650
    Chapter #0.23: start 4204.742000, end 4368.739000
    Metadata:
      title           : 01:10:04.742
    Chapter #0.24: start 4368.739000, end 4533.154000
    Metadata:
      title           : 01:12:48.739
    Chapter #0.25: start 4533.154000, end 4699.403000
    Metadata:
      title           : 01:15:33.154
    Chapter #0.26: start 4699.403000, end 4972.468000
    Metadata:
      title           : 01:18:19.403
    Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Metadata:
      title           : input
      stereo_mode     : left_right
    Stream #0:1(por): Audio: ac3, 48000 Hz, 5.1(side), fltp, 256 kb/s
    Metadata:
      title           : PT-BR: CAPS
    Stream #0:2(eng): Audio: dts (DTS), 48000 Hz, 5.1(side), fltp, 1536 kb/s (default)
    Metadata:
      title           : ENG
    Stream #0:3(por): Subtitle: hdmv_pgs_subtitle
    Metadata:
      title           : PT-BR
Overriding aspect ratio with stream copy may produce invalid files
Output #0, matroska, to 'test.mkv':
  Metadata:
    encoder         : Lavf55.43.100
    Chapter #0.0: start 0.000000, end 137.846000
    Metadata:
      title           : 00:00:00.000
    Chapter #0.1: start 137.846000, end 227.185000
    Metadata:
      title           : 00:02:17.846
    Chapter #0.2: start 227.185000, end 351.643000
    Metadata:
      title           : 00:03:47.185
    Chapter #0.3: start 351.643000, end 536.035000
    Chapter #0.4: start 536.035000, end 648.982000
    Metadata:
      title           : 00:08:56.035
    Chapter #0.5: start 648.982000, end 901.359000
    Metadata:
      title           : 00:10:48.982
    Chapter #0.6: start 901.359000, end 1144.685000
    Metadata:
      title           : 00:15:01.359
    Chapter #0.7: start 1144.685000, end 1338.462000
    Metadata:
      title           : 00:19:04.685
    Chapter #0.8: start 1338.462000, end 1515.723000
    Metadata:
      title           : 00:22:18.462
    Chapter #0.9: start 1515.723000, end 1746.244000
    Metadata:
      title           : 00:25:15.723
    Chapter #0.10: start 1746.244000, end 1976.057000
    Metadata:
      title           : 00:29:06.244
    Chapter #0.11: start 1976.057000, end 2061.476000
    Metadata:
      title           : 00:32:56.057
    Chapter #0.12: start 2061.476000, end 2329.160000
    Metadata:
      title           : 00:34:21.476
    Chapter #0.13: start 2329.160000, end 2400.690000
    Metadata:
      title           : 00:38:49.160
    Chapter #0.14: start 2400.690000, end 2498.413000
    Metadata:
      title           : 00:40:00.690
    Chapter #0.15: start 2498.413000, end 2742.615000
    Metadata:
      title           : 00:41:38.413
    Chapter #0.16: start 2742.615000, end 3057.054000
    Metadata:
      title           : 00:45:42.615
    Chapter #0.17: start 3057.054000, end 3142.556000
    Metadata:
      title           : 00:50:57.054
    Chapter #0.18: start 3142.556000, end 3441.772000
    Metadata:
      title           : 00:52:22.556
    Chapter #0.19: start 3441.772000, end 3575.947000
    Metadata:
      title           : 00:57:21.772
    Chapter #0.20: start 3575.947000, end 3749.204000
    Metadata:
      title           : 00:59:35.947
    Chapter #0.21: start 3749.204000, end 3945.650000
    Metadata:
      title           : 01:02:29.204
    Chapter #0.22: start 3945.650000, end 4204.742000
    Metadata:
      title           : 01:05:45.650
    Chapter #0.23: start 4204.742000, end 4368.739000
    Metadata:
      title           : 01:10:04.742
    Chapter #0.24: start 4368.739000, end 4533.154000
    Metadata:
      title           : 01:12:48.739
    Chapter #0.25: start 4533.154000, end 4699.403000
    Metadata:
      title           : 01:15:33.154
    Chapter #0.26: start 4699.403000, end 4972.468000
    Metadata:
      title           : 01:18:19.403
    Stream #0:0(eng): Video: h264 (H264 / 0x34363248), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 23.98 fps, 1k tbn, 1k tbc (default)
    Metadata:
      title           : input
      stereo_mode     : left_right
    Stream #0:1(eng): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      title           : ENG
      encoder         : Lavc55.66.101 ac3
    Stream #0:2(por): Subtitle: hdmv_pgs_subtitle
    Metadata:
      title           : PT-BR
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:2 -> #0:1 (dts (dca) -> ac3 (ac3))
  Stream #0:3 -> #0:2 (copy)
Press [q] to stop, [?] for help
[dca @ 0000000004f7d3a0] Overread auxiliary data by 32 bits
[dca @ 0000000004f7d3a0] error decoding block
Error while decoding stream #0:2: Invalid data found when processing input
[dca @ 0000000004f7d3a0] Overread auxiliary data by 32 bits4 bitrate=7071.6kbits/s
[dca @ 0000000004f7d3a0] error decoding block
Error while decoding stream #0:2: Invalid data found when processing input
[dca @ 0000000004f7d3a0] Overread auxiliary data by 32 bits5 bitrate=7762.9kbits/s
[dca @ 0000000004f7d3a0] error decoding block
Error while decoding stream #0:2: Invalid data found when processing input
[dca @ 0000000004f7d3a0] Overread auxiliary data by 32 bits2 bitrate=8015.3kbits/s
[dca @ 0000000004f7d3a0] error decoding block
Error while decoding stream #0:2: Invalid data found when processing input
[dca @ 0000000004f7d3a0] Overread auxiliary data by 32 bits3 bitrate=7842.7kbits/s
[dca @ 0000000004f7d3a0] error decoding block
Error while decoding stream #0:2: Invalid data found when processing input
frame=119220 fps=961 q=-1.0 Lsize= 4708393kB time=01:22:52.34 bitrate=7757.1kbits/s
video:4571784kB audio:116470kB subtitle:18062kB other streams:0kB global headers:0kB muxing overhead: 0.044125%

Then running ffmpeg -i test.mkv (this is the output file from the above command) shows the following info about the aspect ratio:

Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080, SAR 1:2 DAR 8:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)

Look at the SAR/DAR value on stream 0:0. It's different from original file. I tried with and without -aspect parameter. I tried using -vf "DAR=16:9" but I get the message:

Filtergraph 'dar=16:9' was defined for video output stream 0:0 but codec copy was selected. Filtering and streamcopy cannot be used together."

How do I keep the aspect ratio without reencode the video?

I am unable to duplicate this issue. Please show the complete ffmpeg console output from your command. — llogan, Dec 8, 2014 at 21:22
Is the new console output from the command above, or from a different command? — llogan, Dec 11, 2014 at 19:29
Same command @LordNeckbeard. I copy and paste on windows console. — Victor Santos, Dec 11, 2014 at 21:37
Can you provide a short sample file so I can attempt to duplicate this issue? — llogan, Dec 11, 2014 at 23:08

Radek Pech · Accepted Answer · 2020-01-20 09:31:21Z

To fix aspect ratio that gets broken after reencoding, try these steps:

use parameter -aspect to force aspect ratio without reencoding:
```
ffmpeg -i input.mkv -c copy -aspect 16/9 output.mkv
```
Alternatively you can use the MKVmerge to do the same:
```
mkvmerge --aspect-ratio 16:9 -o output.mkv input.mkv
```
If soft aspect ratio does not help, you can force it in the reencoding by setting scale and setdar (set display aspect ratio) video filters:
```
ffmpeg -i input.mkv -c copy c:v your_codec -vf "scale=1920:1080,setdar=16/9" output.mkv
```
If even the scale filter does not help, you can reset the video by creating AVS script and then reencoding the file from the script. This way you will keep only the raw video bitstream without any metadata that may consufe the players to use incorrect aspect ratio.
```
ffmpeg -i input.avs -c copy c:v your_codec output.mkv
```
You need a program that will index the original video and then create the AVS file (e.g. on Windows you can use MeGUI and its Tools - File Indexer). You also need correct AviSynth and FFMPEG versions (32/64-bit) to work together.

Here is example of an AVS file:
```
LoadPlugin("/path/to/avisynth/ffms2.dll")
FFVideoSource("/path/to/input.mkv", fpsnum=24000, fpsden=1001, threads=1, colorspace="YUV420P8")
LanczosResize(1920,1080)
```

tjbp · Accepted Answer · 2020-05-19 14:22:16Z

0

-map 0:0 -map 0:1 -map 0:2

ffmpeg -i input.mkv -c:v copy -c:s copy -c:a ac3 -ac 2 -map 0:0 -map 0:1 -map 0:2 -aspect 16:9 test.mkv

if it doesn't work, avoid using "copy" edit a conversion.

edited May 19, 2020 at 14:22

tjbp

1213 bronze badges

answered Jul 23, 2015 at 7:55

Nando Gomes

11 bronze badge

Super User is an English-only site, and all the questions and answers must be in English.
– DavidPostill ♦
Jul 23, 2015 at 8:16
While this may answer the question, it would be a better answer if you could provide some explanation why it does so.
– DavidPostill ♦
Jul 23, 2015 at 8:16

Add a comment |

urbanspaceman · Accepted Answer · 2022-11-07 09:34:50Z

I came across this issue while trying to use yt-dlp (with ffmpeg as a post-processor). Some of the videos seemed to have the wrong SAR to start with (in most cases it should be 1:1, aka. square pixels), and when I converted the videos to h.264 it displayed incorrectly and inconsistently in different software. This seems to have corrected it:

yt-dlp -f 313+140 --merge-output-format mp4 --postprocessor-args "ffmpeg:-c:v libx264 -c:a copy -vf scale=iw:ih,setsar=sar=1,setdar=dar=w/h" "https://www.youtube.com/watch?v=1234567"

In the above I'm using FFmpeg's video filter (-vf), setting the scale to the current input width and height (scale=iw:ih), setting the sample/pixel aspect ratio (sar) to 1, and setting the display aspect ratio (dar) to the same with and height (setdar=dar=w/h). If I didn't define all 3 values it would only display correctly in some software.

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