Thank you. You're right ... my error ... I meant to say 12 bytes (including the 2 bytes for VAD). And it is 10ms/frame. No matter ... thank you for the SPEEX specs. In terms of quality, what SPEEX bit rate compares with G.729 at 8kbps data rate please? Is there some reason why you chose the 20ms frame rate? Do you keep that same frame rate for the different bit rates? The faster frame rate would seem to better adapt to multiple speakers cutting in and out ... yes/no? Btw, 6 bytes/frame at 50 frames/second seems to be 2.4kbps so I'm guessing that the lower rate you mentioned is because of some overhead for VAD in your 6 bytes. At 07:11 PM 5/3/2007 +1000, Jean-Marc Valin wrote:>B. Mitchell Loebel a ?crit : > > How many bits do you have in a frame please and what is your frame rate? > > For example, G.729 (ACELP) has 12 bits/frame including VAD and the frame > > rate is 100/second ... I'm looking for the comparable figures for SPEEX. > >I'm sorry but if G.729 used 12 bits/frame at 100 frames/second, it would >have a bit-rate of 1.2 kbps. G.729 actually uses 10 *bytes* (i.e. 80 >bits) per frame. Speex has 20 ms frames (50 frames per second) and >supports bit-rates that range from 2.15 kbps (6 bytes per frame) to 44 >kbps (110 bytes per frame). > > Jean-Marc--- B. Mitchell Loebel, CEO, VP Engineering 408 425-9920 InstaFlash International Corporation (formerly Minute-Tape International Corporation) -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/speex-dev/attachments/20070503/c1186ec8/attachment.html
B. Mitchell Loebel a ?crit :> Thank you. You're right ... my error ... I meant to say 12 bytes > (including the 2 bytes for VAD). And it is 10ms/frame. No matter ... > thank you for the SPEEX specs. In terms of quality, what SPEEX bit rate > compares with G.729 at 8kbps data rate please?Haven't done formal testing and it depends on whether it's G.729 or G.729A. I'd say probably 8 kbps or 11 kbps.> Is there some reason why > you chose the 20ms frame rate?It's a good value I think. Speex is designed for VoIP, so 10 ms is pretty much useless because you'd be sending about 32 kbps worth of overhead (each packet has 40 bytes for IP+UDP+RTP headers).> Do you keep that same frame rate for the > different bit rates?Yes.> The faster frame rate would seem to better adapt to > multiple speakers cutting in and out ... yes/no?I don't think we should really worry about speakers interrupting each other at 10 ms interval. If that happens, you've got much more important problems than the codec :-)> Btw, 6 bytes/frame at 50 frames/second seems to be 2.4kbps so I'm > guessing that the lower rate you mentioned is because of some overhead > for VAD in your 6 bytes.Well, technically 2.15 kbps would mean 5.375 bytes/frame, but then you need to round up to the next whole byte -- unless you put multiple frames in a packet, in which case it matters. Jean-Marc> At 07:11 PM 5/3/2007 +1000, Jean-Marc Valin wrote: >> B. Mitchell Loebel a ?crit : >> > How many bits do you have in a frame please and what is your frame >> rate? >> > For example, G.729 (ACELP) has 12 bits/frame including VAD and the >> frame >> > rate is 100/second ... I'm looking for the comparable figures for >> SPEEX. >> >> I'm sorry but if G.729 used 12 bits/frame at 100 frames/second, it would >> have a bit-rate of 1.2 kbps. G.729 actually uses 10 *bytes* (i.e. 80 >> bits) per frame. Speex has 20 ms frames (50 frames per second) and >> supports bit-rates that range from 2.15 kbps (6 bytes per frame) to 44 >> kbps (110 bytes per frame). >> >> Jean-Marc > > > --- > B. Mitchell Loebel, CEO, VP Engineering 408 > 425-9920 > InstaFlash International Corporation > (formerly Minute-Tape International Corporation) >
Thank you Jean-Marc. My understanding is that G.729 is a telephone codec, so there must have been some reason why its developers went to 10ms/frame. Do you know why that might be? From a recent post on this list I saw somebody talking about your decoded sample rate being 8KHZ/sec. and then he mentioned that being 160 bytes at 20ms/frame. That said, I take it that your decoded samples are 1 byte wide ... is that correct? We're using G.729 and we'd like to consider SPEEX at sometime in the future. That's why I asked you about the quality comparison. Of course, G.729's decoded samples are 16 bits wide so that's another quality consideration. At 09:30 PM 5/3/2007 +1000, Jean-Marc Valin wrote:>B. Mitchell Loebel a ?crit : > > Thank you. You're right ... my error ... I meant to say 12 bytes > > (including the 2 bytes for VAD). And it is 10ms/frame. No matter ... > > thank you for the SPEEX specs. In terms of quality, what SPEEX bit rate > > compares with G.729 at 8kbps data rate please? > >Haven't done formal testing and it depends on whether it's G.729 or >G.729A. I'd say probably 8 kbps or 11 kbps. > > > Is there some reason why > > you chose the 20ms frame rate? > >It's a good value I think. Speex is designed for VoIP, so 10 ms is >pretty much useless because you'd be sending about 32 kbps worth of >overhead (each packet has 40 bytes for IP+UDP+RTP headers). > > > Do you keep that same frame rate for the > > different bit rates? > >Yes. > > > The faster frame rate would seem to better adapt to > > multiple speakers cutting in and out ... yes/no? > >I don't think we should really worry about speakers interrupting each >other at 10 ms interval. If that happens, you've got much more important >problems than the codec :-) > > > Btw, 6 bytes/frame at 50 frames/second seems to be 2.4kbps so I'm > > guessing that the lower rate you mentioned is because of some overhead > > for VAD in your 6 bytes. > >Well, technically 2.15 kbps would mean 5.375 bytes/frame, but then you >need to round up to the next whole byte -- unless you put multiple >frames in a packet, in which case it matters. > > Jean-Marc > > > At 07:11 PM 5/3/2007 +1000, Jean-Marc Valin wrote: > >> B. Mitchell Loebel a ?crit : > >> > How many bits do you have in a frame please and what is your frame > >> rate? > >> > For example, G.729 (ACELP) has 12 bits/frame including VAD and the > >> frame > >> > rate is 100/second ... I'm looking for the comparable figures for > >> SPEEX. > >> > >> I'm sorry but if G.729 used 12 bits/frame at 100 frames/second, it would > >> have a bit-rate of 1.2 kbps. G.729 actually uses 10 *bytes* (i.e. 80 > >> bits) per frame. Speex has 20 ms frames (50 frames per second) and > >> supports bit-rates that range from 2.15 kbps (6 bytes per frame) to 44 > >> kbps (110 bytes per frame). > >> > >> Jean-Marc > > > > > > --- > > B. Mitchell Loebel, CEO, VP Engineering 408 > > 425-9920 > > InstaFlash International Corporation > > (formerly Minute-Tape International Corporation) > >--- B. Mitchell Loebel, Executive Director 408 425-9920 The Tech Startup Connection (formerly The PARALLEL Processing Connection)