unmuxed cmaf hls trun version

[kidoubled]

using unmuxed cmaf in hls, getting a trun version of 0. I believe I've deduced this is leveraging the dash packager, and if I can set the media_set->version >=2, i'd get trun version 1.

nginx-vod-module/vod/dash/dash_packager.c

Line 1889 in 26f0687

p = mp4_fragment_write_video_trun_atom(p, sequence, first_frame_offset, media_set->version >= 2 ? 1 : 0);

I think this could be sourced from the submodule_context->request params, when in mapped mode, but after that, I lose the path. https://github.com/kaltura/nginx-vod-module/blob/master/ngx_http_vod_module.c#L5286

hoping I'm on the right track, and that someone can help me with the rest. Thanks in advance

[kidoubled]

I found the version parsing from the filename https://github.com/kaltura/nginx-vod-module/blob/master/ngx_http_vod_request_parse.c#L522

which is set here for dash:

nginx-vod-module/vod/dash/dash_packager.c

Line 373 in 26f0687

p = vod_copy(p, "-x3", sizeof("-x3") - 1); // TODO: remove this after deployment

but I can't see how this would be set for unmuxed hls

[kidoubled]

@erankor
would checking for track count =1 and adding a -x3 in one of these locations be a good solution to how to get unmixed cmaf hls to use trun version 1 with signed pts delay?
https://github.com/kaltura/nginx-vod-module/blob/master/vod/manifest_utils.c#L399
https://github.com/kaltura/nginx-vod-module/blob/master/vod/hls/m3u8_builder.c#L206

alternatively, perhaps I could get away with using a sub_filter to turn .m4s into -x3.m4s?

[kidoubled]

testing the subfilter approach using a config similar to this:

location /cmaf/hls/ {
            vod hls;
            vod_hls_force_unmuxed_segments on;
            vod_hls_container_format fmp4;

            sub_filter '.m4s' '-x3.m4s';
            sub_filter_once off;
            sub_filter_types application/vnd.apple.mpegurl;
        }

which seems to be working. I'd be interested to know if there's a better approach.

[erankor]

Hi @kidoubled, out of curiosity, why do you care if it's version 0 or 1?
The URL version (-x3) was added for backward compatibility - at some point I changed the trun version from 0 to 1, but I wanted it to affect only new streams - so that the player won't get a mix of version 0 & version 1.
Btw, I implemented a solution similar to your solution here - #985 (comment)

[erankor]

In our live packager (a more recent project, using some of the code initially written here), I'm always using version 1 for video -
https://github.com/kaltura/media-framework/blob/master/nginx-pckg-module/src/media/mp4/mp4_muxer.c#L316

[kidoubled]

@erankor some newer players don't work well with version 0 / without the signed pts delay... always using version 1 for video makes a great deal of sense these days, and I can see that would occur with almost all modes of operation within the packager, except unmuxed hls, because that ends up using the dash packager code, but without adding the -x3 modifier to the uris. I'll plan to use the subfilter, but would be open to working on a PR if you had thoughts about the best way to address. Is the "right way" to fix this removing the legacy backwards compatibility at this point?

Also, I had noticed #985 (comment) and used it as inspiration for my approach above. Thanks for the project and all the community support over the years.