where to start/split mpeg2-ts

Question

I am writing a server which live streams mpeg2-ts on HTTP and I wondered what's the best position to split an mpeg transport stream. The stream is going to be played by iptv set-top boxes and I have no idea how these devices behave.

I would think that the best place to start a stream is before an I-Frame, but the device might need the PAT and PMT packets before it starts to decode video stream data...

Hypostyle

Did you find any solution?! If TS contain multiple programs (TV programs that captured by DVB-T), how can split it? For example I have a TS file that contain football + cooking + cartoon .How can i split this TS file to 3 mpg files? – Rheumy

I can explain how to do it programmatically (check PAT & rewrite it, grab the appropriate PMT, look for the stream identifiers, extract only the relevant data, .. and you probably have to re-number the packets) - but if all you want to do is to split, you'd better search for a tool (ffmpeg?) – Hypostyle

Answer 1

You can start with every 188-byte TS packet (0x47 is the start code). The MPEG decoder automatically jumps in at the first I frame. You can do tricks like MS Mediaroom does with sending burst I-frames, but this requires heavy changes to your client (and patent royalities).

Loden

Theoretically, yes.. practically I was sometimes able to crash a lame set-top box (which is btw quite popular here) by doing that (no, I don't start at any 0x47, I know it's a TS packet start). Also decoder starts before first I-frame so I see some bad decoded frames for half a sec.. – Hypostyle

Some players require self-initialized TS segments, that is segments that start with a PAT/PMT and I-Frame. Eg: Android 4.4.4 player doesn't like it if there's no PAT/PMT and it won't decode at all. – Extraditable

Answer 2

To be safe you should use self-initializing TS segments. Such segment must include the PAT/PMT and start with an IDR-frame.

For example this is a requirement in the HTTP Live Streaming pantos draft when using I-Frame playlists.

See more: GPAC - Apple HLS Introduction

Extraditable