FFmpeg notes

Get FFmpeg here: https://www.ffmpeg.org

Here are some almost-copy-and-pasteable examples that you can use with the uncompressed TGAs that b2 saves out.

PREFIX in each case refers to the prefix used to save the files. Replace it with the actual prefix you used.

Basic conversion

Convert TGAs and WAVs to mp4 with flac audio, adjusting pixel aspect ratio to match the BBC's slightly thin pixels. (The playback program will hopefully adjust the output accordingly so it's about the right shape.) This roughly matches what b2 does when generating compressed video itself.

ffmpeg -y -f concat -i PREFIX.video_list.txt -f concat -i PREFIX.audio_list.txt -map 0:v:0 -map 1:a:0 -vf "setsar=24/25" -acodec flac output.mp4

Alternatively, you can deal with the aspect ratio by resizing the images. The output resolution in this case will be around 706x576.

ffmpeg -y -f concat -i PREFIX.video_list.txt -f concat -i PREFIX.audio_list.txt -map 0:v:0 -map 1:a:0 -vf "scale=iw*0.96:ih" -acodec flac output.mp4

720p output

Resize to accommodate aspect ratio, then stretch the result and add borders left and right to produce 720p output (1280x720).

ffmpeg -y -f concat -i PREFIX.video_list.txt -f concat -i PREFIX.audio_list.txt -map 0:v:0 -map 1:a:0 -vf "scale=iw*0.96:ih,scale=1280:720:force_original_aspect_ratio=1,pad=width=1280:height=720:x=(out_w-in_w)/2:y=(out_h-in_h)/2:color=black" -acodec flac output.mp4

1080p output

Similarly, but for 1080p (1920x1080).

ffmpeg -y -f concat -i PREFIX.video_list.txt -f concat -i PREFIX.audio_list.txt -map 0:v:0 -map 1:a:0 -vf "scale=iw*0.96:ih,scale=1920:1080:force_original_aspect_ratio=1,pad=width=1920:height=1080:x=(out_w-in_w)/2:y=(out_h-in_h)/2:color=black" -acodec flac output.mp4