avconv stream splitting

--- Streaming script (run once) ---
#!/bin/bash
# Reads video from the Blackmagic Intensity Pro, and splits in into
# two streams.
# One stream is sent to Justin.tv, the other is sent via RTP to two
# local ports (audio and video), where another thread can read selected
# slices and write them to disk.
#
# Steven Bell <botsnlinux@gmail.com>
# 25 March 2013

WEBCAST_SIZE="720x480"
WEBCAST_FPS="20"
WEBCAST_BITRATE="1000k"

RECORD_SIZE="1920x1080"
RECORD_FPS="30"

# Streaming settings
STREAM_KEY="XXXXXX"
STREAM_URL="rtmp://live.justin.tv/app/$STREAM_KEY"
VIDEO_RTP_PORT=1234
AUDIO_RTP_PORT=1236

# Paths
export AVCONV_DATADIR=/home/steven/video/tools/libav/presets/
AVCONV=/home/steven/video/tools/libav/avconv
BMDTOOLS=/home/steven/video/tools/bmdtools

$BMDTOOLS/bmdcapture -m 11 -F nut -f pipe:1 | \
$AVCONV -i - \
        -f pulse -i default \
        -map 0:v \
        -map 1:a \
        -vcodec libx264 -pre:0.0 libx264-main \
        -acodec libmp3lame -ar 44100 -ab 32k \
        -r $WEBCAST_FPS -s $WEBCAST_SIZE -b $WEBCAST_BITRATE \
        -threads 0 \
        -y \
        -f flv "$STREAM_URL" \
        \
        -map 0:v \
        -vcodec mpeg4 -vb 15000k \
        -threads 0 \
        -r $RECORD_FPS -s $RECORD_SIZE \
        -f rtp rtp://127.0.0.1:$VIDEO_RTP_PORT \
        \
        -map 1:a \
        -acodec libmp3lame -ar 44100 -ab 32k \
        -threads 0 \
        -f rtp rtp://127.0.0.1:$AUDIO_RTP_PORT

--- Recording command (run many times) ---
#!/bin/bash
FILENAME=$1

export AVCONV_DATADIR=/home/steven/video/tools/libav/presets
# My avconv seems to puke on rtp-ed mpeg headers
#AVCONV_PATH=/home/steven/video/tools/libav/avconv
AVCONV_PATH=avconv

$AVCONV_PATH -i combined.sdp -vcodec copy -acodec copy -y $FILENAME


--- SDP file ---
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
t=0 0
a=tool:libavformat 55.0.0
m=video 1234 RTP/AVP 96
c=IN IP4 127.0.0.1
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1
m=audio 1236 RTP/AVP 14
c=IN IP4 127.0.0.1
b=AS:32