Transcoding and Dash support

[nherbaut]

I noticed that streama didn't support file transcoding.
Is it your backlog? If not, can you elaborate on how to integrate it from a technical point of view?
I have a project that does transcoding and generates dash segments that works well with dash.js maybe I can work on a way to integrate it.

[dularion]

That would be absolutely fantastic! I was thinking of implementing a node-js runner that uses idle system resources to convert files in the background and make them available to streama when rdy, otherwise they are queued. But immediate transcoding would be even better. Its just not something that I know very much about

[Jeronimo95]

On-the-fly transcoding is something I've been thinking about for a while, but have been working on other issues.

My plan was to create a wrapper around FFMPEG to handle the transcoding. When the video player requests the file, return the transcode.

[nherbaut]

@Jeronimo95
It depends what are the system requirements for the project. It might be resource hungry. For example, I've deployed ampache which performs simple audio transcoding with ffmpeg, and it's already bringing my VPS down to its knees... without proper GPU acceleration, it may not even be feasible to transcode 1 stream in real time. Amazon does propose GPU-accelerated instances that can be used, but the hosting price may not be what the final user expects, especially if the GPU instance is idle most of the time

[nherbaut]

@dularion what are the possibilities for technical integration?
for example, I have a poc (https://github.com/nherbaut/vhg-adaptation-worker) that runs async transcoding and dash chunking tasks that use a transcoding workflow implemented in python and working with with an amqp message broker to accommodate several parallel workers for scalability.
I could wrap it up in a stand-alone docker microservice with a REST api and tell streama to process the transcoding depending on the current load of the system. We also have the java connectors that can pilot the message brokers (we use spring btw)

Another option would be to have a 100% pure java code, relying on ffmpeg or gstreamer under the hood for transcoding

Let me know what would work best

[Jeronimo95]

We could build the transcoder to do both pre-transcoding and live-transcoding. Then make it selectable for the user, by default live-transcoding the files so users don't have to think about it on a new install. We could have options like:

• No Transcoding
• Live Transcoding
  • Transcode Quality
  • Max Simultaneous Streams
• Transcode on upload
  • Delete files after transcode
  • Transcode previously upload files
• Transcode local files folder
  • Output folder (Same location / Different location)

Then the user would have the power to select what they wanted. For something like a small VPS - use the "Transcode on upload" or "No Transcoding". For a home server with a powerful CPU use "Live Transcoding".
The non-live options could be given a lower priority (or have selectable priority) so as to not kill other applications on the system (including streama).

If you take a look at the processes when running a Plex transcode it has the following options, which look similar to FFMPEG, I wouldn't be surprised if they were using it as a base.

/usr/lib/plexmediaserver/Plex Transcoder
-codec:0 h264 -codec:1 ac3 -noaccurate_seek -i 
/mnt/nas01/media/TV/Rick and Morty/Season 03/Rick and Morty S03E09 The ABC's of Beth.mkv
-map0:0 -codec:0 copy -map0:1 -codec:1 aac -ar:148000 -channel_layout:1stereo -b:1256k -f segment
-segment_format matroska -segment_format_options live=1 -segment_time 1 
-segment_header_filenameheader -segment_start_number 0 
-segment_list http://127.0.0.1:32400/video/:/transcode/session/ipq0ylx83ajhun6gkwiuaqsq/75278953-211e-4050-8834-dea2dde5b653/seglist
-segment_list_type csv -segment_list_size 2147483647 -avoid_negative_ts disabled -map_metadata -1 
-map_chapters -1 chunk -%05d -start_at_zero -copyts -y -nostats -loglevel quiet -loglevel_plex error
-progressurl http://127.0.0.1:32400/video/:/transcode/session/ipq0ylx83ajhun6gkwiuaqsq/75278953-211e-4050-8834-dea2dde5b653/progress

From this we can sort of tell that passing the video/segments/progress/etc back to Plex via http://127.0.0.1:32400/video/:/transcode/

As for system requirements it depends on how many streams the user wants to do at once. A Core 2 Duo 2.0 GHz should be able to do a single 720p transcode. I previously had a home server running a
intel G1840 that could do two-three transcode playbacks.

We should make it as easy for the end-user as possible, I think a solution that is contained within streama would be best and make it the most flexible.

[Shrinks99]

Will this transcoder support multiplexing video? No need to actually transcode a file that is already in H264, sometimes an MKV container just needs to be changed over to an MP4.

This basically just takes way less time and CPU power while changing the file type and not reducing the video quality as far as I understand it.

[Jeronimo95]

Yeah will definitely do that. If it's just the container that needs to be changed no sense to completely decode and reencode the data.

[nherbaut]

Please note that if we want to support adaptive streaming (DASH/HLS) to impove users' quality of experience, it is necessary to down-scale the videos to genereate low-def chunks. This requires a transcoding pass. 2017-09-29 3:43 GMT+02:00 Jeremy Ryan <notifications@github.com>:

…

Yeah will definitely do that. If it's just the container that needs to be changed no sense to completely decode and reencode the data. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#440 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AA6pNy44Bz9Y9ozyh4d4LQOGT_ORRLaEks5snEs5gaJpZM4PjxIt> .

-- Nicolas Herbaut +33671997796

[dali99]

Also, heavilly requested feature lacking from plex and other platforms is proper ordered chapters support. This allows TV series that ship with the same intro save space by only storing the intro/ending sequence once, and just playing that in a set time on the other MKVs

Also allows easilly autoskipping intros, and playing only the intros.