Discussion in 'HD/HDR-FOX T2 Customised Firmware' started by dooferdog, Sep 16, 2012.
Hi guys. What is the procedure please for ripping mp3 from a video track from the humax?
This can be done on the Humax using the OPT Extract Audio option, However it's worth noting that the MP3 file that it produces is MP2 (layer7) audio rather than the more common MP2 (Layer 3). It is an MP3 file but some MP3 player won't play it. It is possible to convert the Layer7 MP3 to Layer 3 MP3 using ffmpeg but the Humax does not do this because the Humax CPU isn't up to the job. More notes on the Wiki HERE
I find I can create proper MP3s easily using VLC to transcode, including turning MP4 iPlayer radio grabs into MP3.
Thanks again. I shall investigate the above.
Does anyone know how to up the quality to 256k? I have tried the following change to execute.jim
puts [exec /mod/bin/ffmpeg -y -benchmark -v 0 \
-i $rfile -f mp3 -ab 256k \
But it is taking a very long time to process.
The process used to extract MP3 from the video stream has been selected to extract 'as-is' e.g. to not carry out ANY transcoding, due to the extra loading that this would place on the CPU. It is possible to transcode to MP2 Layer3 (the more common MP3 version) but that has not been done for the same reason - Lack of processing power
O.K. Thanks for that.
It won't 'up the quality' anyway, It's a bit like re-sizing a 3 Mega pixel picture to 30 Mega pixels there isn't any more detail added
But doesn't the audio encode at 256k when you record something?
How do you mean? When the Humax records the incoming TV/radio streams all it does is capture the digital data that makes up that stream on the broadcast multiplex. You get what's sent, there is no encoding going on and the Humax does not deal in analogue at all (until the final output digital-to-analogue conversion). There is no value in trying to transcode the data to a higher bit rate, it might even make it worse.
You can encode MP2 (layer 7 or layer3) at any bit rate from say 8k to 800k it's up to the broadcaster, the point is that if the original is at 8k then transcoding it up to 256k won't improve it, and if it's already at 256k it doesn't need transcoding
You are quite correct, if I use MediaInfo to look at an audio only recording I get this
ID : 1602 (0x642)
Menu ID : 5760 (0x1680)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Mode : Joint stereo
Codec ID : 3
Duration : 1h 59mn
Bit rate mode : Constant
Bit rate : 160 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 137 MiB (17%)
Language : English
So 160Kbps is the best I can expect.
The broadcasters do change audio bitrates around fairly regularly too - particularly on the HD channels.
Separate names with a comma.