We've successfully made the jump to using the Adobe Media Server 4.5 to provide video to both Desktop computers and iOS devices, (HLS and HDS). Very exciting.
However, with increasing requirements to provide closed captioning for accessibility, we need to be able to provide closed captioning for our videos displaying on iOS and in the Flash player.
What is the best approach to provide closed captioning using these new FMS technologies?
AMS 5 is coming up with exciting release of delivery closed captions on HLS /HDS/RTMP.
However for customers still on FMS 4.5, we have guidlines for content publisher or content makers to have closed caption compatiable messages inside data itself required for HDS/HLS/RTMP.
Wait for sometime for the documents to go live.
I have cc working on FMS 4.5 for everything but the iPhone. The iPhone player will not support CC. Only Apple can fix this. I'm using a custom deployment of OSMF with TTML formatted cc files for video on demand. I'm not using RTMP because of firewall/support issues. For HTML5 I'm using the LeanBackPlayer with SRT formatted cc files. We built a JAVA exe that builds the TTML and SRT cc files from delimited text files or Excel. We auto built cross server authentication between ASP.NET/IIS and Apache. Getting everyting setup and working was pretty difficult. Far more difficult than anticipated.
It can be done with 4.5.
Thanks, David ... I'm hoping to find a player that understands the output from Adobe's Broadcast SDK 3.0, which processes SEI from H264 and adds CC (not sure what format, yet) to the fragments in the .f4f files.
Yeah. It's always been within the realm of possibility to patch something together if you've got timed text files (or some other external caption file) at your disposal.
However, it's considerably more challenging to devise a workflow that preserves the live caption data. AMS5 supposedly supports this, but Adobe's been mum on how to actually make it work.
Here is the Adobe Media Server Documentation on Closed Captioning implementation.
Adobe Media Server comes with a sample player in the directory Adobe Media Server5/samples/videoplayer/videoplayer.html
This player can play a video with Closed Captions. By default Closed captions is turned off in the configuration files.
<GenerateCCInfo>false</GenerateCCInfo> This needs to be set to true in Server.xml
AMS supports captions for Live streams for RTMP and HDS streaming. The encoder has to pass the captions in an AMF message onCaptionInfo as mentioned in the documentation
For HLS streaming
HLS players natively support streams with captions in H264 SEI NALU. AMS passes these streams without modifying.
If the captions are in Timed text format ( Apple defined clcp timed text format) then AMS provides a tool to embed these timed text captions inside an H264 SEI NALU.
I was able to get displayed captions from OnCaption packets HDS output (f4f/f4x) files. The trick was finding the right player: in Adobe Media Server 5.0.1, use /opt/adobe/ams/samples/videoPlayer/videoplayer.html. The osmf player didn't work for me.
Could you be a bit more specific regarding CC please?
What is the format that I need the CC to be on? How do i stream it to the clients for both HDS and HLS.
I dont have much expirience with CC and the adobe media server guide does not help me much.
I already enable <GenerateCCInfo>true</GenerateCCInfo>
I would appreciate it
I realized that in order to enable CC for HDS the httpd.config file needs to be eddited under /hds-vod
with the following info....
I sill need to figure out what is teh format of the CC fileas as well as how to embed that into the stream to the clients...
THen i need to figure out HLS....
Do you have any information regatrding Closed Caption on AMS 5 other than
I don't find the implementation user friendly. I would really appreciate if you can provide some guidance regarding the implementation
Could you please clarify when you stated "The encoder has to pass the captions in an AMF message onCaptionInfo as mentioned in the documentation" section of your message.
I read the documentation but i could not get the steps to follow...
Implementation is not friendly at all. Nothing about AMS that is friendly or easy. I have cc working for video on demand with a custom OSMF media player and would be willing to help you. I had a difficult time of it and would be willing to share what I know. David Addison, Portland, Maine. You can find me on the web. I run several dedicated Adobe streaming servers.