Re: [mythtv-users] frustrating comments about sample rates (what not to do)
Ok so I was wrong. Why would I question Isaac? STUPID! Well long story short I'm still getting this odd behavior when watching live tv. I'm running 0.18 under knoppmyth r5a12 with ivtv 0.3.7b. Here's the mpeg info on my live-tv buffer which was causing these time discrepancy issues ID_FILENAME="ringbuf1.nuv" ID_VIDEO_FORMAT=0x1002 ID_VIDEO_BITRATE=540 ID_VIDEO_WIDTH=480 ID_VIDEO_HEIGHT=480 ID_VIDEO_FPS=29.970 ID_VIDEO_ASPECT=1. ID_AUDIO_CODEC=mp3 ID_AUDIO_FORMAT=80 ID_AUDIO_BITRATE=224000 ID_AUDIO_RATE=48000 ID_AUDIO_NCH=2 ID_LENGTH=3453 ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] frustrating comments about sample rates (what not to do)
Isaac Richards wrote: Why is there a problem? The sampling rate is always read from the file, not the database, on playback. Isaac That was my first impression as well when skimming over the source, but apparently (at least to my feeble eyes) not the case. If I set the sample rate to 32000 it records at 48000 because it can't or won't change the sample rate with ivtvctl and there's a time discrepancy (I can only say for sure this happens when watching while recording but it definately doesn't happen after commercial flagging). If I set the sample rate to 48000 it records at 48000 and everything is fine. So I'd have to assume it's getting 32000 from the db because all the mpg headers say 48000 regardless of what I set. It's the only thing I change and it only changes in the db. I can't say for sure where this is happening cause I haven't found it yet but when and if I do I'll post it. Larry ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] frustrating comments about sample rates (what not to do)
On Monday 29 August 2005 06:03 pm, Larry Symms wrote: > I know the difference, the problem is, the user who doesn't go digging > through code would have no indication that changing the sample rate for > recording profiles of an mpeg device would have negative effects, which > aren't immediately obvious. Why would I change the rate you ask? The > default alsamixer settings for my audio card (which uses the Via Envy24 > chipset) sets "multi track rate locking" to on, so I set the alsamixer > multi track sample rate to 44.1kHz so that it would work with TV and > music. I changed the recording profile rates to 44.1kHz and didn't > realize there was a problem for a few weeks because this only happens > when watching recordings as they're recording or buffered live TV which > I do very rarely. Why is there a problem? The sampling rate is always read from the file, not the database, on playback. Isaac ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] frustrating comments about sample rates (what not to do)
I know the difference, the problem is, the user who doesn't go digging through code would have no indication that changing the sample rate for recording profiles of an mpeg device would have negative effects, which aren't immediately obvious. Why would I change the rate you ask? The default alsamixer settings for my audio card (which uses the Via Envy24 chipset) sets "multi track rate locking" to on, so I set the alsamixer multi track sample rate to 44.1kHz so that it would work with TV and music. I changed the recording profile rates to 44.1kHz and didn't realize there was a problem for a few weeks because this only happens when watching recordings as they're recording or buffered live TV which I do very rarely. Donavan Stanley wrote: On 8/29/05, Larry Symms <[EMAIL PROTECTED]> wrote: In mpegrecorder.cpp it states "// only 48kHz works properly." regarding audio sample rates which I have tested and proven true. What happens is a discrepancy in displayed time and actual position in the recording. This leads to skipping back when trying to skip forward because myth is miscalculating the current position based on time elapsed. The problem is that the comments in Recording Profiles in TV Settings in Myth frontend say: "Sets the audio sampling rate for your DSP. Ensure that you choose a sampling rate appropriate for your device. btaudio may only allow 32000." This implys that not only is it ok to change the sampling rate from the default but that it is recomended. This is not the case. Do not be deceived, 48000 is the only acceptable setting for mpeg encoders unless you never watch recordings while they're recording. When playing recordings while they are recording the sample rate is gathered from the codec settings in the db rather than the mpeg header. If any of this is incorrect by all means correct me but I'm 99% sure this is the case based on the code I've gone through and the tests I've conducted. The big thing you appear to be missing is the btaudio and mpegrecorder have nothing to do with each other. If you have a card which uses btaudio you're going to be using nupplevideoencoder. ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] frustrating comments about sample rates (what not to do)
On 8/29/05, Larry Symms <[EMAIL PROTECTED]> wrote: > In mpegrecorder.cpp it states "// only 48kHz works properly." regarding > audio sample rates which I have tested and proven true. What happens is > a discrepancy in displayed time and actual position in the recording. > This leads to skipping back when trying to skip forward because myth is > miscalculating the current position based on time elapsed. The problem > is that the comments in Recording Profiles in TV Settings in Myth > frontend say: "Sets the audio sampling rate for your DSP. Ensure that > you choose a sampling rate appropriate for your device. btaudio may > only allow 32000." This implys that not only is it ok to change the > sampling rate from the default but that it is recomended. This is not > the case. Do not be deceived, 48000 is the only acceptable setting for > mpeg encoders unless you never watch recordings while they're > recording. When playing recordings while they are recording the sample > rate is gathered from the codec settings in the db rather than the mpeg > header. If any of this is incorrect by all means correct me but I'm 99% > sure this is the case based on the code I've gone through and the tests > I've conducted. The big thing you appear to be missing is the btaudio and mpegrecorder have nothing to do with each other. If you have a card which uses btaudio you're going to be using nupplevideoencoder. ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
[mythtv-users] frustrating comments about sample rates (what not to do)
In mpegrecorder.cpp it states "// only 48kHz works properly." regarding audio sample rates which I have tested and proven true. What happens is a discrepancy in displayed time and actual position in the recording. This leads to skipping back when trying to skip forward because myth is miscalculating the current position based on time elapsed. The problem is that the comments in Recording Profiles in TV Settings in Myth frontend say: "Sets the audio sampling rate for your DSP. Ensure that you choose a sampling rate appropriate for your device. btaudio may only allow 32000." This implys that not only is it ok to change the sampling rate from the default but that it is recomended. This is not the case. Do not be deceived, 48000 is the only acceptable setting for mpeg encoders unless you never watch recordings while they're recording. When playing recordings while they are recording the sample rate is gathered from the codec settings in the db rather than the mpeg header. If any of this is incorrect by all means correct me but I'm 99% sure this is the case based on the code I've gone through and the tests I've conducted. ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
