[linux-dvb] Keep bitrates below 10Mbps...
abraham.manu at gmail.com
Sat Oct 29 08:37:12 CEST 2005
Josef Wolf wrote:
>[ I hope I am on-topic here. I have considered to post this to the
> tuxbox-forum, but decided to post it here because it has more to
> do with stream encodings than with the dbox2.]
>I'm trying to transport live streams over a 10BaseT network. With
>most channels, there is no problem. But on some programs (most notably
>the german ARD) the bitrate is changing pretty much. After a lot of
>investigations, i've got some assumptions:
>- Most of the bandwidth is consumed by the video-pid (pid 101). This is
> not really a surprise. I mention this here only because I need a reason
> to ignore the other PIDs :)
>- Most of the time the bitrate on the video-pid is quite low (about
> 2000..3500 TS packets per second, which gives something below 7MBps).
> But sometimes (every 10..20 minutes) the bitrate raises dramatically
> for a couple of seconds (sometimes just one second, sometimes up to 20
> seconds) and comes down again to the 2000..3500 range. I really don't
> understand what is going on here. How come this dramatic raise without
> increase in the motion or in picture-details? Is this raise really
> caused by the video stream?
>- Next, I checked how much stuffing (via adaptation field) is inserted.
> It seems to me that about 6..8% stuffing is inserted.
>My guess is that with recoding the TS into PS, it should be possible to
>avoid this stuffing. In addition, the TS header (another 2%) can be
>avoided. With a little luck, this might be sufficient to get the bitrate
>below 10MBps (check footnote ).
>Can anyone confirm or correct my assumptions or have any other idea what
>might be going wrong here?
Since the TS is constituted of more than the Video ES, the bandwidth
occupied might very well depend on other factors.
I remember Johannes once saying that the EIT rate on the German Das
Erste is quite high.
>I would like to try this recoding (TS->PS). Extracting PES from the TS
>is not really a probem. But unfortunately, I could not find any
>description how PS streams are to be constructed. Any pointers?
You can probably, check out replex from the Metzler bros,
More information about the linux-dvb