Regression in ffmpeg 6

[m1k1o]

There is a regression since ffmpeg 6 that breaks the segmenting.

Test script:

# Generate test file of 20 sec, with keyframes every 2sec
ffmpeg -loglevel warning -fflags +genpts \
    -f lavfi -i testsrc=duration=20:size=1280x720:rate=30 \
    -f lavfi -i sine=frequency=1000:duration=20 \
    -c:v libx264 -g 60 \
    -c:a aac -b:a 192k \
    -f mp4 -y -movflags +faststart /tmp/test.mp4;

# Seek to 10 sec and create three 2s segments (at 12,14,16)
ffmpeg -loglevel warning -ss 10 -i /tmp/test.mp4 -to 16 -copyts -c copy \
    -f segment \
    -segment_time_delta 0.2 \
    -segment_format mpegts \
    -segment_times 12,14,16 \
    -segment_start_number 5 \
    -segment_list_type csv \
    -segment_list pipe:1 /tmp/test_%03d.ts;

We can set up a simple dockerfile:

ARG VERSION=3.22
FROM alpine:${VERSION}
RUN apk add --no-cache ffmpeg
ENTRYPOINT [ "ffmpeg" ]

And then run scripts above with different versions.

docker build --build-arg VERSION=3.14 -t alpine-ffmpeg:3.14 .
docker run --rm alpine-ffmpeg:3.14 -version

Versions prior 6

ffmpeg version 4.2.4 (from alpine:3.11)
ffmpeg version 4.3.1 (from alpine:3.12)
ffmpeg version 4.3.3 (from alpine:3.13)
ffmpeg version 4.4.1 (from alpine:3.14)
ffmpeg version 5.0.3 (from alpine:3.16)
ffmpeg version 5.1.4 (from alpine:3.17)

test_005.ts,0.000000,12.000000
test_006.ts,12.000000,14.000000
test_007.ts,14.000000,16.000000
test_008.ts,16.000000,16.166667

Versions after 6

ffmpeg version 6.0.1 (from alpine:3.18)
ffmpeg version 6.1.1 (from alpine:3.19)
ffmpeg version 6.1.2 (from alpine:3.21)

test_005.ts,0.000000,16.166667

It seems that it requires now relative offet to the seeked time in segment_times instead of the absolute time.

Modified segmenter script:

ffmpeg -loglevel warning -ss 10 -i /tmp/test.mp4 -to 16 -copyts -c copy \
    -f segment \
    -segment_time_delta 0.2 \
    -segment_format mpegts \
    -segment_times 2,4,6 \
    -segment_start_number 5 \
    -segment_list_type csv \
    -segment_list pipe:1 /tmp/test_%03d.ts;

New output:

test_005.ts,0.000000,12.000000
test_006.ts,12.000000,14.000000
test_007.ts,14.000000,16.000000
test_008.ts,16.000000,16.166667

[m1k1o]

Hotfix in a4b556b

[m1k1o]

Additionally, sincle v6 in ffprobe's frame output pkt_pts_time was renamed to pts_time:

ffprobe /tmp/test.mp4 -skip_frame nokey -show_entries frame -select_streams v -of json

Before:

{
    "media_type": "video",
    "stream_index": 0,
    "key_frame": 1,
    "pkt_pts": 0,
    "pkt_pts_time": "0.000000",
    "pkt_dts": 60416,
    "pkt_dts_time": "3.933333",
    "best_effort_timestamp": 0,
    "best_effort_timestamp_time": "0.000000",
    "pkt_duration": 512,
    "pkt_duration_time": "0.033333",
    "pkt_pos": "23057",
    "pkt_size": "7976",
    "width": 1280,
    "height": 720,
    "pix_fmt": "yuv444p",
    "sample_aspect_ratio": "1:1",
    "pict_type": "I",
    "coded_picture_number": 0,
    "display_picture_number": 0,
    "interlaced_frame": 0,
    "top_field_first": 0,
    "repeat_pict": 0,
    "chroma_location": "left",
    "side_data_list": [
        {
            "side_data_type": "H.26[45] User Data Unregistered SEI message"
        }
    ]
}

After:

{
    "media_type": "video",
    "stream_index": 0,
    "key_frame": 1,
    "pts": 0,
    "pts_time": "0.000000",
    "pkt_dts": 60416,
    "pkt_dts_time": "3.933333",
    "best_effort_timestamp": 0,
    "best_effort_timestamp_time": "0.000000",
    "pkt_duration": 512,
    "pkt_duration_time": "0.033333",
    "duration": 512,
    "duration_time": "0.033333",
    "pkt_pos": "23057",
    "pkt_size": "7990",
    "width": 1280,
    "height": 720,
    "crop_top": 0,
    "crop_bottom": 0,
    "crop_left": 0,
    "crop_right": 0,
    "pix_fmt": "yuv444p",
    "sample_aspect_ratio": "1:1",
    "pict_type": "I",
    "coded_picture_number": 0,
    "display_picture_number": 0,
    "interlaced_frame": 0,
    "top_field_first": 0,
    "repeat_pict": 0,
    "chroma_location": "left",
    "side_data_list": [
        {
            "side_data_type": "H.26[45] User Data Unregistered SEI message"
        }
    ]
}

[m1k1o]

According to docs:

Specify a list of split points. times contains a list of comma separated duration specifications, in increasing order. See also the segment_time option.

According to this, following code should return two segments, one 2sec long and another 4sec long:

ffmpeg -loglevel warning -ss 10 -i /tmp/test.mp4 -to 16 -copyts -c copy \
    -f segment \
    -segment_time_delta 0.2 \
    -segment_format mpegts \
    -segment_times 2,4 \
    -segment_start_number 5 \
    -segment_list_type csv \
    -segment_list pipe:1 /tmp/test_%03d.ts;

But in reality we get two three ~2s segments:

test_005.ts,0.000000,12.000000
test_006.ts,12.000000,14.000000
test_007.ts,14.000000,16.166667

It seems like it is not skipping keyframes in the video.