[FFmpeg-user] Converting Interlaced MPEG-2 video in MKV container to MP4 container

[Gary Cattelino]

I'm using the latest windows ffmpeg build. To change interlaced MPEG-2 video from a mkv to mp4 container, the command I'm using is "ffmpeg -i input.mkv -vcodec copy -acodec copy out.mp4".  I'm concerned that the out.mp4 file has a variable frame rate, while the input.mkv file has a constant frame rate of 29.970:

input.mkv:

Width: 720 pixels

Height: 480 pixels

Display aspect ratio: 16:9

Frame rate mode: Constant

Frame rate: 29.970 fps

Standard: NTSC

Color space: YUV

Chroma subsampling: 4:2:0

Bit depth: 8 bits

Scan type: Interlaced

Scan order: Top Field First



out.mp4:

Width: 720 pixels

Height: 480 pixels

Display aspect ratio: 16:9

Original display aspect ratio: 16:9

Frame rate mode: Variable

Frame rate: 24.077 fps

Original frame rate: 29.970 fps

Minimum frame rate: 20.000 fps

Maximum frame rate: 30.303 fps

Standard: NTSC

Color space: YUV

Chroma subsampling: 4:2:0

Bit depth: 8 bits

Scan type: Interlaced

Scan order: Top Field First



What's the best way to change this video to a MP4 container and maintain a constant frame rate without transcoding? I tried to force interlace support (-ilme), but the windows build doesn't seem to support that.

Thanks.