Date: Sun, 14 Dec 1997 12:57:16 +0200 (EET) From: Petri Helenius <pete@sms.fi> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: hasty@rah.star-gate.com (Amancio Hasty), multimedia@FreeBSD.ORG, don@partsnow.com Subject: RTP tools (was: Re: Remote and Voice control) Message-ID: <199712141057.MAA28409@silver.sms.fi> In-Reply-To: <199712140538.GAA01124@labinfo.iet.unipi.it> References: <199712132104.NAA06292@rah.star-gate.com> <199712140538.GAA01124@labinfo.iet.unipi.it>
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Luigi Rizzo writes: > > controller and helping Petri for an rtp to mtv glue logic. > > this is a very interesting project. Yes, I'm not sure how much you cut off from Amancio's email, I'll expand a little. The idea is that you run this like: mrtp VVV.VVV.VVV.VVV/video_port AAA.AAA.AAA.AAA/audio_port | mtv - And it will play a MPEG AV stream off the network, with A/V synchronization at the playback. The problem this addresses is that the usual case is that we have two RTP streams in the network which must be multiplexed together to an ISO MPEG system stream. Amancio is doing the system stream generation and I've put together a single stream RTP decoder so far which works like this: mrtp VVV.VVV.VVV.VVV/video_port | mtv - And you'll get the video off the network. Or: mrtp AAA.AAA.AAA.AAA/audio_port | mpg123-m - And you'll have a MPEG-audio net radio. The idea here is that one uses multicast but there is no reason why the tool could not be used with unicast also. (Actually it checks for unicast/multicast address before calling things like IP_ADD_MEMBERSHIP) So if you want to improve on your transcoder you might want to change it into a transmitter, reading .mp2 and .mp3 files and transmitting them with RTP headers over multicast. The next step might be to add encryption to both the transmitter and receiver. The good side about both mtv and mpeg123 is that they are very tolerant to bad MPEG data, so the wrapper can pass partial frames into them and they'll just klick and hiss and life goes on. (unlike mpeg_play which complains and quits or crashes) Also, I observed that mtv is about 20-35% more performant on the same hardware than similar function performed under Win95. I only wish we could get full screen operation for mtv in the future (Tristan?) Pete
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