Issues changing the aspect ratio of MKV

[Mephesto]

The rest are fine but this one is being gay and refuses to have its aspect ratio changed. Original is 960x720 but it should display 1280x720. Every other MKV is easily editted by the Header editor from MKVMergeGUI but this one isn't budging. I tried extracting raw streams from it and re-muxing but it still fails.
What's a robust way I can force a 16:9 aspect ratio?

[El Heggunte]

Start by posting the Mediainfo report about the pesky file


Mephesto

[Mephesto]

Haggard one:

General
Unique ID                                : 204113466707373420429179307909926146859 (0x998ED2E1D54F2AAE92880E4BA2A4D32B)
Complete name                            : M:\0f.mkv
Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 83.8 MiB
Duration                                 : 21mn 37s
Overall bit rate                         : 541 Kbps
Encoded date                             : UTC 2010-02-22 21:41:31
Writing application                      : mkvmerge v5.9.0 ('On The Loose') built on Dec  9 2012 15:37:01
Writing library                          : libebml v1.3.0 + libmatroska v1.4.0

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L5.0
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 16 frames
Muxing mode                              : Header stripping
Codec ID                                 : V_MPEG4/ISO/AVC
Width                                    : 960 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Original display aspect ratio            : 4:3
Frame rate mode                          : Variable
Original frame rate                      : 23.976 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Writing library                          : x264 core 129 r2230 1cffe9f
Encoding settings                        : cabac=1 / ref=16 / deblock=1:1:1 / analyse=0x3:0x133 / me=umh / subme=11 / psy=0 / mixed_ref=1 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=0 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=16 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=200 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.70 / qpmin=10 / qpmax=51 / qpstep=4 / ip_ratio=1.40 / aq=2:1.00
Language                                 : English
Default                                  : Yes
Forced                                   : No

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : HE-AAC / LC
Codec ID                                 : A_AAC
Duration                                 : 21mn 37s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz / 22.05 KHz
Compression mode                         : Lossy
Delay relative to video                  : 33ms
Default                                  : Yes
Forced                                   : No

Text
ID                                       : 3
Format                                   : UTF-8
Codec ID                                 : S_TEXT/UTF8
Codec ID/Info                            : UTF-8 Plain Text
Default                                  : Yes
Forced                                   : No

Heres one of a different video of the same show without the aspect ratio issue:

General
Unique ID                                : 199766914292520660782223221370785709467 (0x9649B54D78DB6B59992E296EDFED3D9B)
Complete name                            : M:\0e.mkv
Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 83.6 MiB
Duration                                 : 21mn 39s
Overall bit rate                         : 540 Kbps
Encoded date                             : UTC 2010-02-22 21:41:31
Writing application                      : mkvmerge v5.9.0 ('On The Loose') built on Dec  9 2012 15:37:01
Writing library                          : libebml v1.3.0 + libmatroska v1.4.0

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L5.0
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 16 frames
Muxing mode                              : Header stripping
Codec ID                                 : V_MPEG4/ISO/AVC
Width                                    : 960 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Original frame rate                      : 23.976 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Writing library                          : x264 core 129 r2230 1cffe9f
Encoding settings                        : cabac=1 / ref=16 / deblock=1:1:1 / analyse=0x3:0x133 / me=umh / subme=11 / psy=0 / mixed_ref=1 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=0 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=16 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=200 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.70 / qpmin=10 / qpmax=51 / qpstep=4 / ip_ratio=1.40 / aq=2:1.00
Language                                 : English
Default                                  : Yes
Forced                                   : No

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : HE-AAC / LC
Codec ID                                 : A_AAC
Duration                                 : 21mn 39s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz / 22.05 KHz
Compression mode                         : Lossy
Delay relative to video                  : 33ms
Default                                  : Yes
Forced                                   : No

Text
ID                                       : 3
Format                                   : UTF-8
Codec ID                                 : S_TEXT/UTF8
Codec ID/Info                            : UTF-8 Plain Text
Default                                  : Yes
Forced                                   : No

Only difference is in the problematic video it says "original DAR is 4:3" but normally I can change this in MKVMerge.

[hello_hello]

I'm pretty sure "original aspect ratio" is the aspect ratio as it was written to the video stream. Display aspect ratio is the aspect ratio set at the container level.

The problem is, some players give preference (or only pay attention to) the video stream aspect ratio, while others ignore it if there's an aspect ratio written to the MKV. I'm pretty sure my Sony Blu-ray player is big on the video stream aspect ratio so changing it with MKVMergeGUI doesn't helpt. If memory serves me correctly (I haven't had to think about it for a long time) MPC-HC (or maybe LAV filters these days) lets you choose. If you happen to use MPC-HC, try right clicking on the video and under "Video Frame" uncheck "keep aspect ratio". I think that'll get it to use the container aspect ratio. Or.....
Look in Video Decoder under Internal Filters. There's an aspect ratio option there.

[hello_hello]

If you want to change the stream aspect ratio and don't mind battling with a command line tool:
http://forum.doom9.org/showthread.php?t=152419&highlight=ffmpeg+Bitstream+Modifier+Muxer

I've used it myself to change the stream aspect ratio on the odd occasion. I can't remember if it also creates a file with a container aspect ratio. If not you can always remux the MKV it creates with MKVMergeGUI.

[El Heggunte]

hello_hello explained it well --- the correct/intended aspect ratio also depends on the decoder (software or firmware), and under some circumstances, a buggy video driver might be "the root of all evil" ^_^

[Mephesto]

If it is a decoding error, it only happens on this vid out of 100 of similar ones so I don't know what went wrong. Even if this can be fixed by fiddling with ffdshow/LAV, the common viewer these videos are intended for wouldn't know how to do that. My rule of thumb is that if I can't figure out, I shouldn't expect most people downloading my stuff to be able to either.

hello_hello, ok I looked at the thread but what bitstream filter do I use in the command line just to change sar?

Script: ffmpeg1 -i "0f (2).mkv" -vcodec copy -acodec copy -vbsf h264_changesps=sar=16:9 "0f (3).mkv"

I don't know what the -vbsf is for either.

[poisondeathray]

what bitstream filter do I use in the command line just to change sar?

Script: ffmpeg1 -i "0f (2).mkv" -vcodec copy -acodec copy -vbsf h264_changesps=sar=16:9 "0f (3).mkv"

I don't know what the -vbsf is for either.

-vbsf specifies "video bitstream filter"

But the --sar x:y for your video should be 4:3, not 16:9 because

16/9 = 960/720 * 4/3

Display Aspect Ratio = Frame Aspect Ratio * Sample Aspect Ratio

[Mephesto]

And which filter do I need to type in, it's not accepting sar by itself.
You're probably right that I should enter 4:3 but it said SAR was already 4:3 so I assumed this had to be changed since the video wasn't displaying 16:9.

[poisondeathray]

What do you mean by it said SAR was already 4:3 ? ffmpeg said or something else ?

That is the filter. "h264_changesps=sar=16:9" , you have it correct except for the value should be 4:3

ffmpeg1 -i "0f (2).mkv" -vcodec copy -acodec copy -vbsf h264_changesps=sar=4:3 "0f (3).mkv"

You need to use that specific binary from roozhou, other ffmpeg builds won't do it

[poisondeathray]

IF it's still not behaving, demux it, use the ffmepg command on the elementary video stream, remux streams with mkvmerge and set the DAR as well . That way both the bitstream and container AR flags are set. Those are the only 2 places AR information is stored and read by media players

[Mephesto]

Okay I got it to work. First, every AR works with that modded ffmpeg except 4:3. When I set it to 16:9 the AR was 24:10 when I played the video, setting to 4:3 made it 4:3, setting it to 4000:2999 made it 16:9. So every value worked except the one that I needed. Love it when this shit happens!

I just set SAR to 4:3 whether or not it really changed anything, then set the DAR with MKVMerge and it's finally 16:9 like it's supposed to be. I operated on the MKV not raw stream.

Thanks guys. I put a hiatus on a new TV show I was ripping and encoding back in late 2012 which I only resumed today so I forgot what happened with this SAR-screwed episode. I set the display aspect ratio on MeGUI before encoding but I thought this set the DAR not SAR so I'm confused. Meh.

[hello_hello]

You're not confusing Storage Aspect Ratio (resolution) with Sample Aspect Ratio (pixel aspect ratio) are you? I'm not sure if there's any real distinction between sample aspect ratio and pixel aspect ratio or whether a new SAR was introduced just to cause confusion with storage aspect ratio.

I'm pretty sure ffmpeg's SAR is Sample Aspect Ratio, so it makes sense if a 4:3 SAR produced a 16:9 DAR.... I think. If MediaInfo only reports Display Aspect Ratio and Original Aspect Ratio is gone, the stream and container aspect ratio should be the same.

How did you set the DAR in MeGUI? MeGUI uses DAR in the script which it converts to SAR for the x264 command line, but I think it does it's calculating when the script is loaded. Changes to the DAR in the script without reloading it might have no effect.