On Tue, Jun 10, 2025 at 13:21:49 -0400, Mark Filipak wrote: > My 5-step method is now a 4-step method, but, apparently, any further > efficiency is not possible. I cover that at the bottom of this message. [...] > Isn't it curious that subtitles don't work in Step 1, but they do work in > Step 5?
No, it isn't. In step 1, you are trying to "copy" PGS image-based subtitles into MP4. MP4 supports _only_ text-based subtitles in the mov_text format/codec. Nothing else. ffmpeg cannot do that, because it's just not possible. (MP4 is quite restrictive. That's why it's easier switching to a player supporting more flexible containers than trying to convert everything to MP4.) In step 4, SubtitleEdit apparently converts the PGS subtitles to SRT - likely by OCR. (Which is something ffmpeg cannot really do, even though there is an OCR filter, converting video to text.) SRT in turn can be reencoded to mov_text by ffmpeg - that's why step 5 works. > FACT: Subtitles do work in mp4, so don't say that they don't work. Only text-based mov_text subtitles. > FACT: FFmpeg is able to make subtitles in mp4 if the subtitles come from an > srt. Partially because SRT is also text-based (and because someone implemented the encoding, obviously). > FACT: FFmpeg is not able to make subtitles in an mp4 if it is also making > video. No tool is capable of placing image-based subtitles into MP4 as a separate track. You must either super-impose them onto the video, or convert them to text (which ffmpeg cannot, as you correctly state). Cheers, Moritz _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
