Get the codec_name of a specific stream - json

Question

I need to extract the codec_name of the second video stream (artwork) of a video file.
So I do this :
$ ffprobe -hide_banner -v error -show_streams -of json Resurrection_Sunday_Online_Experience_12_April_2020_5.30pm_New_Creation_Church.mp4 | jq . > ffmpeg_output.json
The json file look like this :
$ cat ffmpeg_output.json
{
"streams": [
{
"index": 0,
"codec_name": "h264",
"codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
"profile": "Main",
"codec_type": "video",
"codec_time_base": "1411877/84712500",
"codec_tag_string": "avc1",
"codec_tag": "0x31637661",
"width": 854,
"height": 480,
"coded_width": 864,
"coded_height": 480,
"has_b_frames": 0,
"sample_aspect_ratio": "1:1",
"display_aspect_ratio": "427:240",
"pix_fmt": "yuv420p",
"level": 31,
"color_range": "tv",
"color_space": "bt709",
"color_transfer": "bt709",
"color_primaries": "bt709",
"chroma_location": "left",
"refs": 1,
"is_avc": "true",
"nal_length_size": "4",
"r_frame_rate": "30/1",
"avg_frame_rate": "42356250/1411877",
"time_base": "1/90000",
"start_pts": 0,
"start_time": "0.000000",
"duration_ts": 677700960,
"duration": "7530.010667",
"bit_rate": "387395",
"bits_per_raw_sample": "8",
"nb_frames": "225900",
"disposition": {
"default": 1,
"dub": 0,
"original": 0,
"comment": 0,
"lyrics": 0,
"karaoke": 0,
"forced": 0,
"hearing_impaired": 0,
"visual_impaired": 0,
"clean_effects": 0,
"attached_pic": 0,
"timed_thumbnails": 0
},
"tags": {
"language": "und",
"handler_name": "VideoHandler"
}
},
{
"index": 1,
"codec_name": "aac",
"codec_long_name": "AAC (Advanced Audio Coding)",
"profile": "-1",
"codec_type": "audio",
"codec_time_base": "1/48000",
"codec_tag_string": "mp4a",
"codec_tag": "0x6134706d",
"sample_fmt": "fltp",
"sample_rate": "48000",
"channels": 2,
"channel_layout": "stereo",
"bits_per_sample": 0,
"r_frame_rate": "0/0",
"avg_frame_rate": "0/0",
"time_base": "1/48000",
"start_pts": 0,
"start_time": "0.000000",
"duration_ts": 361441280,
"duration": "7530.026667",
"bit_rate": "125374",
"max_bit_rate": "129296",
"nb_frames": "352970",
"disposition": {
"default": 1,
"dub": 0,
"original": 0,
"comment": 0,
"lyrics": 0,
"karaoke": 0,
"forced": 0,
"hearing_impaired": 0,
"visual_impaired": 0,
"clean_effects": 0,
"attached_pic": 0,
"timed_thumbnails": 0
},
"tags": {
"language": "und",
"handler_name": "SoundHandler"
}
},
{
"index": 2,
"codec_name": "mjpeg",
"codec_long_name": "Motion JPEG",
"profile": "192",
"codec_type": "video",
"codec_time_base": "0/1",
"codec_tag_string": "[0][0][0][0]",
"codec_tag": "0x0000",
"width": 1280,
"height": 720,
"coded_width": 1280,
"coded_height": 720,
"has_b_frames": 0,
"sample_aspect_ratio": "1:1",
"display_aspect_ratio": "16:9",
"pix_fmt": "yuvj420p",
"level": -99,
"color_range": "pc",
"color_space": "bt470bg",
"chroma_location": "center",
"refs": 1,
"r_frame_rate": "90000/1",
"avg_frame_rate": "0/0",
"time_base": "1/90000",
"start_pts": 0,
"start_time": "0.000000",
"duration_ts": 677702430,
"duration": "7530.027000",
"bits_per_raw_sample": "8",
"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": 1,
"timed_thumbnails": 0
}
}
]
}
I tried this but it does not extract the codec_name properly
$ cat ffmpeg_output.json | jq '[select(.streams[].codec_type=="video")][1].codec_name'
null
I also noticed it selected all the streams :
$ cat ffmpeg_output.json | jq '[select(.streams[].codec_type=="video")][1]' | grep codec_type
"codec_type": "video",
"codec_type": "audio",
"codec_type": "video",
Can you help me ?

Answer 1

Your jq filter is simply incorrect. Your select() expression is wrong. Remember the select() expression returns a Boolean value and your condition .streams[].codec_type=="video" is asserted true for two of the provided input objects i.e. for streams with "index": 0 and "index": 2, and for each of these true conditions, the filter prints all the 3 objects i.e. replicates the whole JSON because the select() was at the top level.
You need to make the select() after .streams
.streams[] | select(.codec_type=="video").codec_name
For selecting a object at a specific index, use the standard array notation .[0], .[1]
[ .streams[] | select(.codec_type=="video") ][1] | .codec_name

Answer 2

You don't need JQ for this particular case.
$ ffprobe -hide_banner -v error -of compact=nk=1:p=0 -select_streams v:1 -show_entries stream=codec_name video.mp4
h264