How to detect anamorphic video with FFProbe?

Question

This is the output I get using FFProbe for a video I'm certain is anamorphic. I've converted it as a test with ffmpeg and the results are consistent with the video having a different PAR and DAR (video is squished). I ran some command line params to fix anamorphic video and it worked. Possibly my diagnosis is incorrect, the PAR and DAR are just plain wrong?

The code I used to "correct" the anamamorphic is

--custom-anamorphic --display-width 1280 --keep-display-aspect --modulus 8 --crop 0:0:0:0

Is there an additional command with FFProbe to detect for anamorphic? So far I'm just seeing if the sample_aspect_ratio and display_aspect_ratio are the same or not.

Additionally, a ratio of 0:1 seems incorrect. My video is not infinitely wide. Is there a bug with FFProbe output?

This is the command

-print_format json -show_format -show_streams {originalFilePath}

FFProbe version N-54233-g86190af built on Jun 27 2013 outputs the following:

"Output{
    \"streams\": [
        {
            \"index\": 0,
            \"codec_name\": \"h264\",
            \"codec_long_name\": \"H.264/AVC/MPEG-4AVC/MPEG-4part10\",
            \"profile\": \"Main\",
            \"codec_type\": \"video\",
            \"codec_time_base\": \"1/5994\",
            \"codec_tag_string\": \"avc1\",
            \"codec_tag\": \"0x31637661\",
            \"width\": 1280,
            \"height\": 720,
            \"has_b_frames\": 0,
            \"sample_aspect_ratio\": \"0: 1\",
            \"display_aspect_ratio\": \"0: 1\",
            \"pix_fmt\": \"yuv420p\",
            \"level\": 31,
            \"r_frame_rate\": \"2997/100\",
            \"avg_frame_rate\": \"2997/100\",
            \"time_base\": \"1/2997\",
            \"start_pts\": 0,
            \"start_time\": \"0.000000\",
            \"duration_ts\": 204100,
            \"duration\": \"68.101435\",
            \"bit_rate\": \"3894381\",
            \"nb_frames\": \"2041\",
            \"disposition\": {
                \"default\": 0,
                \"dub\": 0,
                \"original\": 0,
                \"comment\": 0,
                \"lyrics\": 0,
                \"karaoke\": 0,
                \"forced\": 0,
                \"hearing_impaired\": 0,
                \"visual_impaired\": 0,
                \"clean_effects\": 0,
                \"attached_pic\": 0
            },
            \"tags\": {
                \"creation_time\": \"2013-05-0318: 33: 37\",
                \"language\": \"eng\",
                \"handler_name\": \"AppleAliasDataHandler\"
            }
        },
        {
            \"index\": 1,
            \"codec_name\": \"aac\",
            \"codec_long_name\": \"AAC(AdvancedAudioCoding)\",
            \"codec_type\": \"audio\",
            \"codec_time_base\": \"1/44100\",
            \"codec_tag_string\": \"mp4a\",
            \"codec_tag\": \"0x6134706d\",
            \"sample_fmt\": \"fltp\",
            \"sample_rate\": \"44100\",
            \"channels\": 2,
            \"bits_per_sample\": 0,
            \"r_frame_rate\": \"0/0\",
            \"avg_frame_rate\": \"0/0\",
            \"time_base\": \"1/44100\",
            \"start_pts\": 0,
            \"start_time\": \"0.000000\",
            \"duration_ts\": 3003392,
            \"duration\": \"68.104127\",
            \"bit_rate\": \"125304\",
            \"nb_frames\": \"2933\",
            \"disposition\": {
                \"default\": 0,
                \"dub\": 0,
                \"original\": 0,
                \"comment\": 0,
                \"lyrics\": 0,
                \"karaoke\": 0,
                \"forced\": 0,
                \"hearing_impaired\": 0,
                \"visual_impaired\": 0,
                \"clean_effects\": 0,
                \"attached_pic\": 0
            },
            \"tags\": {
                \"creation_time\": \"2013-05-0318: 33: 37\",
                \"language\": \"eng\",
                \"handler_name\": \"AppleAliasDataHandler\"
            }
        }
    ],
    \"format\": {
        \"filename\": \"\\\\\\\\dell690\\\\vsf\\\\_asset_intake\\\\v2\\\\ed69c939-4fe1-40dd-a045-db72ed2e0009\\\\original\\\\USTC_Overview2.mov\",
        \"nb_streams\": 2,
        \"format_name\": \"mov,
        mp4,
        m4a,
        3gp,
        3g2,
        mj2\",
        \"format_long_name\": \"QuickTime/MOV\",
        \"start_time\": \"0.000000\",
        \"duration\": \"68.100000\",
        \"size\": \"34267583\",
        \"bit_rate\": \"4025560\",
        \"tags\": {
            \"major_brand\": \"qt\",
            \"minor_version\": \"537199360\",
            \"compatible_brands\": \"qt\",
            \"creation_time\": \"2013-05-0318: 33: 37\"
        }
    }
}"

Answer 1

After bringing it to the FFMpeg team, I see that 0:1 means that the PAR is undefined and if both are undefined they will always be equal-- This case is then easy to detect.

Answer 2

To detect if a video is anamorphic you need to check for a sample_aspect_ratio that is not 1:1. However a sample_aspect_ratio of 0:1 means it is not specified. In this case, if display_aspect_ratio is also not specified (0:1) then it is non-anamorphic. However if the display_aspact_ratio is specified then we need to compare width:height with the display_aspact_ratio, if they are the same then the video is non-anamorphic, if they are different the video is anamorphic.

IsAnamorphic=
if sample_aspect_ratio=="1:1" then false
else if sample_aspact_ratio != "0:1" the true
else if display_aspect_ratio =="0:1" then false
else if display_aspect_ratio!=width:height then true
else false