HLS implementation with FFmpeg

Question

I am trying to implement HLS using FFmpeg for transcoding + segmenting but have been facing a couple of issues that have been bugging me for the past week.

Issue

Webserver currently receives live MP4 fragments being recorded on-the-go and needs to take care of transcoding and segmentation.

As mp4 fragments are being received, they need to be encoded. Then segmented. If i run a segmenter (be it ffmpeg or apple mediastreamsegmenter), every mp4 fragment is being treated as a VOD by itself and I'm not being able to integrate them as part of a larger live event implementation.

I thought of a solution where every time I receive an mp4 fragment, I first use fmpeg to concatenate it with previous ones to form the larger mp4 that I then pass to be segmented for HLS. That did not work either because the entire stream has to be re-segmented each and every time and existing TS fragments replaced by new ones that are similar yet shifted in time.

Implementation 1

ffmpeg -re -i fragmentX.mp4 -b:v 118k -b:a 32k -vcodec copy -preset:v veryfast -acodec aac -strict -2 -ac 2 -f mpegts -y fragmentX.ts

I manage the m3u8 manifest on my own, deleting old fragments and appending new ones.

When validating the stream, I find it stacked with EXT-X-DISCONTINUITY tags making the stream unwatchable.

Implementation 2

First combine latest fragment with overall.mp4

ffmpeg -i "concat:newfragment.mp4|existing.mp4" -c copy overall.mp4

Then pass the combination to ffmpeg for HLS segmentation

ffmpeg -re -i overall.mp4 -ac 2 -r 20 -vcodec libx264 -b:v 318k -preset:v veryfast -acodec aac -strict -2 -b:a 32k -hls_time 2 -hls_list_size 3 -hls_allow_cache 0 -hls_base_url /Users/JosephKalash/Desktop/test/350/ -hls_segment_filename '350/fragment%03d.ts' -hls_flags delete_segments 350/index.m3u8

Concatenation is not perfect and there are noticeable glitches where the fragments are supposed to be stitched. Segmentation replaces older fragments and the manifest is rewritten as if it's a new HLS stream every time ffmpeg is called.

I cannot figure out how to get this to work properly.

Any ideas?

Answer 1

Solved by relying on nginx rtmp module which turned out to be suited for the above implementation.