Transcode HLS m3u8 to MP4 and include text track

ffmpegvideo

Is it possible with FFMPEG to convert a m3u8 to a MP4 and keep the captions (text) track?

When looking at the Apple stream, https://devimages.apple.com.edgekey.net/streaming/examples/bipbop_4x3/bipbop_4x3_variant.m3u8 I see that the video stream makes mention of Closed Captions, but I can't seem to find a way to extract them.

Stream #0:0: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, smpte1
70m/smpte170m/bt709), 400x300, Closed Captions, 29.92 fps, 29.92 tbr, 90k tbn, 1
80k tbc

The multiple attempts I have made transcode to mp4 but it drops the captions.

I have used VLC on the manifest and it has "subtitles" but after transcode the mp4 doesn't.

Used the command:
ffmpeg -i https://devimages.apple.com.edgekey.net/streaming/examples/bipbop_4x3/bipbop_4x3_variant.m3u8 -c copy -bsf:a aac_adtstoasc out.mp4

Best Answer

I did manage to pull together enough pieces on information to complete this. It is a combination of 3 commands.

Using ffmpeg version 2.8.4

First, the playlist segments need to be merged into a single MPEG-TS file:

ffmpeg -i [playlist_url].m3u8 -c copy [filename].ts

Next, we need to extract the Closed Captions from the file:

ffmpeg -f lavfi -i "movie=[filename_from_last_step].ts[out0+subcc]" [filename].srt

Note: I could only get it to work if the ts file and the cmd's current path matched.

Lastly, you merge the ts and srt file and transcode to MP4:

ffmpeg -i [filename_from_first_step].ts -i [captions].srt -c:v copy -bsf:a aac_adtstoasc -c:s mov_text [out_file_name].mp4

This will give you a MP4 with the captions embedded, as well as a stand-alone srt file if your player doesn't support embedded captions.

Related Solutions

Set MP4 thumbnail

Try to use ffmpeg -disposition option along with -map.

ffmpeg -i video.mp4 -i image.png -map 0 -map 1 -c copy -c:v:1 png -disposition:v:1 attached_pic out.mp4

More information can be found in ffmpeg documentation:

Also, please note, it's not guaranteed that the image you use will be showed in a video preview or as a file tumbanail, because different software programs may not use embedded thumbnails at all.

Linux – Using ffmpeg to make a movie from png files

This is the wrong syntax for passing multiple images as input to ffmpeg. Please have a look at the FFmpeg Wiki guide on creating a video slideshow and the image2 demuxer options.

You need to tell it to use three digits for the sequence numbers, and start at 84, i.e.

ffmpeg -start_number 84 -i island_sizes-CSH\(II\)-%03d.png output.mpg

Some further tips:

MPEG-1 as a video codec is less than optimal and gives you bad quality at high file sizes. Unless you want compatibility for old devices or computers (or Windows XP without any codecs), scratch that and use an MPEG-4 Part 10 encoder (H.264), such as libx264:
```
ffmpeg -i … -c:v libx264 out.mp4
```
For a tutorial on x264 options (how to change the quality etc.) check the x264 encoding guide.
PNG files use an RGB pixel format, which is not supported in normal video codecs. With MPEG-1 it does not matter, but with MPEG-4 codecs it would, since ffmpeg would automatically convert the pixel format to non-subsampled YUV. In that case you need to translate this to chroma-subsampled formats such as YUV 4:2:0, otherwise your video might not play in most applications:
```
ffmpeg -i … -c:v libx264 -pix_fmt yuv420p out.mp4
```