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#mythtv IRC Logs for 2007-02-14

---Logopened Wed Feb 14 00:00:15 2007
00:01<rtsai1112>Captain_Murdoch: huh?
00:01<Captain_Murdoch>you had 2 sessions open.
00:01<rtsai1112>I see a bunch of netsplits. I only log in from one place via "screen" :).
00:01<rtsai1112>but yeah, I'm up to 1112 now, so someone thinks I'm already in here
00:01<Captain_Murdoch>so like the thing where you can have 2 exact pictures side-by-side and cross your eyes and they look 3D, I was saying you could do that with your chat windows.
00:02<Captain_Murdoch>you were still in as rtsai when you logged in as rtsai1112.
00:02<rtsai1112>i have all those messages filtered out
00:02<rtsai1112>but if I am desparate, I can get the same effect by running emacs with two X buffers in the same window :)
00:05<rtsai1112>so are audio packets extremely simple or something? In transcode.cpp, I see the AudioReencocdeBuffer, but I was expecting to see some kind of "struct" somewhere with fields like "volume", "pitch", etc.
00:07<xris>hahahaha... flashplayer streaming directly from mythweb!!
00:07<Captain_Murdoch>rtsai1112: audio packets are just bytes of data samples.
00:08<Captain_Murdoch>the rate they go up/down is the pitch, the highness/lowness is the volume.
00:10<rtsai1112>so what if you have simultaneous high and low-pitched tones?
00:10<rtsai1112>and what about stereo, rear-channel, etc.?
00:10<Captain_Murdoch>the tones are spread out over lots of samples though
00:11<rtsai1112>so many samples with the same timecode?
00:11<Captain_Murdoch>Myth raw audio is only outputted in stereo, and I'm not sure how the left/right are interleaved, it might be right-int, left-int, right-int, left-int, but not sure.
00:12<Captain_Murdoch>there aren't any timecodes in the raw data, it's just 48000 samples per second per channel.
00:12<Captain_Murdoch>or 41000, etc..
00:12<rtsai1112>and what does each sample contain?
00:12<Captain_Murdoch>AC3, MP3, etc. are encoded and may have the other things you're talking about.
00:12<Captain_Murdoch>each "sample" is just a point in time (1/48000 of a second) and what the value was at that point in time.
00:12<rtsai1112>well, ok. but in transcode.cpp, we're just operating on raw audio, right?
00:13<rtsai1112>and if "time" is the x-axis, what is represented by the y-axis (presumably the "sample")?
00:14<Captain_Murdoch>Geoffrey did that code originally. if you look, he keeps track of the timecode for the last amount of data in the buffer I think. it may be best to encapsulate that some and kept the timecodes and the data somehow for correlating with video frames.
00:14<rtsai1112>i will eventually want to keep all of the audio in memory, at least to start out
00:14<Captain_Murdoch>if you have a waveform, say 60hz, that cyles up/down 60 times per second. the 48000 samples are the vertical value on that waveform at each of those 48000 points in time.
00:15<Captain_Murdoch>that's compressed
00:15<rtsai1112>well, metadata
00:15<rtsai1112>like "silence"
00:15<rtsai1112>kind of like I do for "blankness" for blank-frame detetion,e tc.
00:15<rtsai1112>or something
00:15<rtsai1112>but I need an idea of what I am working with
00:16<rtsai1112>so no, not all the actual audio
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00:17<Captain_Murdoch>yeah. I can see keeping things like that. I do so in my FrameInfoEntry
00:18<Captain_Murdoch>so you'll need to look at the sample rate of the audio (ie, 1/48000 of a second, 1/41500, etc.) and convert that into the FPS of the video to know what X number of samples correspond to frame Y in the video.
00:18<rtsai1112>you're still too far ahead of me. I'm still trying to figure out exactly what a "waveform" and "sample" are.
00:19<Captain_Murdoch>silence would be all 0's or anything flat really.
00:19<rtsai1112>am I operating on just bytes, or something more structured?
00:19<Captain_Murdoch>think of the waveform as being on a graph.
00:19<rtsai1112>e.g., does silence require the same amount of bytes as loud noise?
00:19<rtsai1112>(for raw audio data)
00:20<Captain_Murdoch>the byte position is your X, the Y is the height of the waveform at that byte position (aka sample)
00:20<Captain_Murdoch>yes, the byterate is constant
00:20<Captain_Murdoch>in raw audio
00:20<rtsai1112>but each sample is multiple bytes
00:21<rtsai1112>are there "frames" like with video (e.g., XxY pixels for one frame)?
00:21<rtsai1112>For example, if I think about it like music, I was thinking that each sample could be, say 16 bits, where each bit represents some musical tone. If the bit is 1, that tone is being played. If the bit is 0, the tone is not being played.
00:21<Captain_Murdoch>so, if you know that a video frame is 1/29.97 of a second, and you convert that to 48000's of a second, that means that a video frame lasts about 1601 audio samples at 48000hz sampling rate.
00:22<rtsai1112>but I don't know if that's the wrong way to think about it
00:22<Captain_Murdoch>yeah, that's the wrong way. you need to think of it like a waveform on a piece of graph paper. the value of the sample is the height of the wave at that point in time.
00:22<rtsai1112>for human hearing, i guess each 'sample' (to use my musical example) would be however many bits it takes to represent the range of hearing pitch
00:22<rtsai1112>Oh :P
00:23<rtsai1112>how many dimensions of data are we talking about, for a single instant in time?
00:24<rtsai1112>like, a single instant of video data has three dimensions: each pixel has an x, y, and color value
00:25<Captain_Murdoch>2 dimesions. time = X axis, sample = Y axis.
00:25<rtsai1112>and the sample all by itself represents pitch and volume?
00:26<Captain_Murdoch>yes, the min/max is the volume, the speed at which they go from min to max and vice versa is the pitch.
00:26<Captain_Murdoch>a 1hz audio sample goes from min to max and back to min 1 time per second.
00:26<Captain_Murdoch>the amplitude of that 1hz audio is determined by the actual min/max values themselves. lower values = lower volume.
00:27<Captain_Murdoch>or lower absolute value since we're talking about positive and negative numbers since the sample is a signed 16-bit number.
00:27<rtsai1112>OK. So one sample actually represents some length of time, not an infinitesimally small amount of time
00:27<rtsai1112>(e.g., it's not a sound "point")
00:28<rtsai1112>yes ?
00:28<Captain_Murdoch>if you're capturing at 48000hz (samples per second), then there are 48000 16-bit samples that make up that one second of time.
00:28<rtsai1112>OK. Or, 1 sample represnets 1/48000th of a second
00:28<rtsai1112>the amplitude is the volume
00:29<rtsai1112>pitch would be how many times the graph oscilates between min/max within that fixed "width" of the graph
00:30<Captain_Murdoch>yes, how many times it oscillates in one second of samples. and that's a full cycle, so min/max/min, not just min/max. ie, a 60hz signal hits the max 60 times in one second.
00:30<rtsai1112>where 60hz is the pitch here, and not the sample rate
00:30<rtsai1112>(just so I'm clear)
00:31<rtsai1112>so one sample is a pure tone? Is hearing multiple tones (like a musical chord) then simply different samples all being "played" very quickly after each other, like simulating motion video with lots of rapidly-played still frames?
00:32<Captain_Murdoch>yes, 60hz pitch.
00:35<Captain_Murdoch>individual samples have nothing to do with tones really, it's the relationship of the samples when they are put together. consider a sample value of 32000. if it is one out of many that are all the same value, then the audio is actually silent at that point in time. if it is at the top of a min/max/min cycle, then the pitch at that 32000 sample is determined by how fast the sample went from min to max and back again.
00:42<Captain_Murdoch>so I guess none of the devs mind about requiring MySQL 5 after 0.21 since no one replied to that post I made.
00:42<Captain_Murdoch>actually, not requiring 3.23.x that is, we'd allow v4
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01:16<hads>3.23 is ancient surely people can handle the upgrade by now.
01:21<Captain_Murdoch>I still run 3.23... :) I actually built another VM the other night with 5.x in it so I can switch some night after my wife goes to bed and Myth is idle.
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01:22<hads>Well, there you go then... People can handle the upgrade :)
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01:50<xris>there. flv playback checked into svn.
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10:53<MrGandalf>janneg: there?
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10:58<janneg>MrGandalf: yes
10:59<MrGandalf>have any idea why myth won't compile in debug mode in 12730: undefined reference to `last_coeff_flag_offset_8x8'
10:59<MrGandalf>x86_32 cpu, and it's only used in that case
11:00<MrGandalf>but it is defined.. I don't understand
11:00<janneg>since it is declared static in a different compilation unit
11:01<janneg>but I don't know why it works in ffmpeg
11:01<MrGandalf>get rid of the static?
11:02<MrGandalf>k, that seems to work now. thanks
11:04<janneg>MrGandalf: but I "fixed" that already in
11:05<Sembiance>FREE THE MALLOCS!!!!
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11:15<MrGandalf>janneg: not in my merged tree for some reason.. dunno
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14:45<Snow-Man>Don't suppose someone could commit something to double-check I didn't break the commits mailing list, hmm?
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14:51<j-rod>Snow-Man: I gotcha
14:52<Snow-Man>That looks like it worked, anyone on the list see it come through yet?
14:53<j-rod>hrm, although it looks like maybe that shouldn't have been changed... ah well, can always revert it...
14:53<jams>change 12794 ?
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14:57<jams>then yes I received the commit email =)
14:58<Snow-Man>Cool, thanks. :)
14:58<Snow-Man>Just modified the server to bounce mail coming from outside claiming to be from one of the local domains.
14:58<jams>j-rod- added a new screen
14:59<j-rod>jams: ooh, nice
14:59<j-rod>btw, got the install booting under kvm, got sidetracked, haven't played w/it a whole lot since
14:59<Snow-Man>You won't believe how much mail gets because people set up servers named '' for their mythtv stuff...
15:00<jams>j-rod- no trouble
15:00<j-rod>Snow-Man: hahahahahaha
15:00<j-rod>jams: someone distracted me by giving me an hdhomerun
15:00<Snow-Man>j-rod: That shit ain't right. And their upstream apparently ignores mail sent to their abuse@ address.
15:01<Snow-Man>So now it'll get bounced. :)
15:01<Snow-Man>The one that really annoyed me was the guy who had a misconfigured cron job that sent a mail every 20 minutes..
15:02<j-rod>you should parse the headers and look for an originating IP and ping-flood them from osuosl...
15:03[~]j-rod hopes he doesn't have a rogue box on his own network... ;)
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15:11<janneg>j-rod: anything heard from nxp re SAA7162?
15:12<j-rod>jams: got updated iso? I've actually got a spare system ready for it...
15:12<j-rod>janneg: not a peep out of them. :(
15:12<Snow-Man>j-rod: Not unless you run
15:13<j-rod>Snow-Man: phew, not me...
15:14<janneg>j-rod: :( but as expected
15:14<Snow-Man>heh, apparently I'm bouncing some spam now too
15:14<jams>j-rod- not yet want to get those X screens complete before making a new one
15:14<jams>nvidia works, but want to finish ati and intel
15:14<j-rod>janneg: yeah, you were right, writing a driver from scratch is probably considerably easier than even getting a reply...
15:15<j-rod>jams: ok, np, I'll burn what I've got
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15:30<JoeyJoeJo>I'm not sure if I should be asking this here or not, but is there any way that I can help out with getting myth to run on the ps3?
15:30<jams>j-rod- after it's installed I can make my updated packages available
15:30<xris>JoeyJoeJo: how good are you at coding?
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15:31<Snow-Man>You'd have to start by getting linux on it...
15:31<JoeyJoeJo>xris: I hate to admit it, but probably not good enough...
15:32<JoeyJoeJo>is anyone actively working on this already though?
15:32<j-rod>JoeyJoeJo: step 1) send me your PS3
15:32<j-rod>then I'll work my ass off on it
15:32<j-rod>I've actually been wanting to get one solely for that, but can't justify the cost
15:33<j-rod>though *supposedly*, our desktop team is going to get one, since we're aiming to support it out of the box with Fedora 7
15:33<j-rod>so I may be able to heist cycles on that one, if it materializes
15:33<j-rod>(though I can imagine lunch time cycles being spent rather differently...)
15:34<JoeyJoeJo>well, if anything other than coding (testing or whatever) needs to be done, I'd love to help
15:35<j-rod>JoeyJoeJo: get fedora on it, install the packages from, report what's broke
15:35<j-rod>axel's looking for help on this front, supposedly, the ppc packages he builds aren't working on it atm, but access to a PS3 is limited...
15:35<JoeyJoeJo>j-rod: I should be able to do that..
15:35<j-rod>get on the atrpms-users or atrpms-devel mailing list too
15:35<janneg>JoeyJoeJo: if any video player is available you could try to play some videos and test if it is fast enough.
15:36<janneg>I heard the framebuffer is not capable of playing back SD content
15:36<JoeyJoeJo>janneg: why wouldn't it be fast enough? I thought the ps3's processor was really fast (can't remember numbers)
15:37<xris>JoeyJoeJo: probably lack of video card drivers
15:37<j-rod>because sony locks out access to the video card
15:37<j-rod>you have to pass all video through a frame buffer
15:37<janneg>linux on ps3 has no direct hardware access to thr graphics controller and sony's hypervisor seems to be slow
15:37<j-rod>very sub-optimal for video
15:37<JoeyJoeJo>man, that sucks
15:39[~]j-rod knows a few clever X hackers in the office he'd like to see have some time in front of a PS3...
15:40<JoeyJoeJo>I hear that.. my dream is to have the ps3 be my HD frontend/game emulator
15:41<Snow-Man>Lemme know if anything weird happens with the lists and whatnot.
15:42<Snow-Man>Looks ok to me and I'm done screwing with stuff. :)
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16:10<briand>curses! foiled again!
16:10[~]briand mutters incoherently.
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19:09<xris>anyone know where chutt's been lately?
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19:37<janneg>xris: there he is
19:37[~]briand snickers.
19:42<xris>all I had to do was ask, I guess. :)
19:43<briand>heh.. well, if that's the case:
19:43<briand>anyone know where gbee's been lately?
19:44<janneg>probably in his bed.
19:44<xris>right now? I'd guess he's asleep
19:44<xris>it's almost 3 AM where he is (if I did my math right -- stupid DST)
19:45<xris>make that 1 AM
19:45<janneg>no, 01:44 in england
19:45<janneg>2:45 here, sigh
19:45<xris>well, stupid DST, then. I can never remember which is GMT-7 or GMT-8
19:54<briand>heheh... no, I kinda figured he was probably asleep.. I was just trying out xris's "summoning technique" :)
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20:10<HighLife245>hey guys I have a card here from a friend, I have no manual but the box says it's a V-Stream Studio TV Terminator card
20:10<HighLife245>made by kworld
20:10<HighLife245>Does anyone know if this card is supported in ubuntu?
20:11<gardengnome>try #ubuntu or #mythtv-users
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20:12<HighLife245>woops srry didn't see the development part at the top, my bad
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20:23<briand>how can you not see that? isn't the channel topic amongst the first blast of text received after /joining a channel? :rolls eyes:
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---Logclosed Thu Feb 15 00:00:36 2007