Re: Hauppage hvr-950q au0828 transfer problem affecting audio and perhaps video
I am definitely seeing what you are saying with regards to the channel flipping back and forth. Do you know what size URBs are being delivered? If you've got a hacked up version of usbaudio.c, how about adding a printk() line which dumps out the URB size and send me a dump? Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com I produced the dump of URB sizes you requested by adding that printk() line. The results are at http://pastebin.com/f26f29133 -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Hauppage hvr-950q au0828 transfer problem affecting audio and perhaps video
On Fri, Dec 4, 2009 at 9:31 AM, John S Gruber johnsgru...@gmail.com wrote: I produced the dump of URB sizes you requested by adding that printk() line. The results are at http://pastebin.com/f26f29133 Hi John, This is good info (especially since you have kernel timestamps enabled). Did you have a specific reference to the USB audio spec which said the packet size has to be on an integer boundary? I took a look at the spec last night and didn't see anything to that end. Do you have a proposed patch to usbaudio.c which works for you? If so, feel free to send it along and I will review and provide comments. If the spec does not require the packets to be on an integer boundary, perhaps the driver just improperly assumes they will be (and they were for whatever developer wrote the original code). Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Hauppage hvr-950q au0828 transfer problem affecting audio and perhaps video
On Fri, Dec 4, 2009 at 10:43 AM, Devin Heitmueller dheitmuel...@kernellabs.com wrote: On Fri, Dec 4, 2009 at 9:31 AM, John S Gruber johnsgru...@gmail.com wrote: I produced the dump of URB sizes you requested by adding that printk() line. The results are at http://pastebin.com/f26f29133 Hi John, This is good info (especially since you have kernel timestamps enabled). Did you have a specific reference to the USB audio spec which said the packet size has to be on an integer boundary? I took a look at the spec last night and didn't see anything to that end. Do you have a proposed patch to usbaudio.c which works for you? If so, feel free to send it along and I will review and provide comments. If the spec does not require the packets to be on an integer boundary, perhaps the driver just improperly assumes they will be (and they were for whatever developer wrote the original code). Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com Hi Devin, You might look at this: http://www.usb.org/developers/devclass_docs/Audio2.0_final.zip File: Frmts20 final.pdf Sections 2.3.1.3, 2.3.1.4 and 2.3.1.5 on page 15 This is from release 2.0 from 5/31/2006 Also http://www.usb.org/developers/devclass_docs/frmts10.pdf Sections 2.2.2, 2.2.3 and 2.2.4 on page 9. This is the 1998 1.0 release. Thanks for your offer to review my patch. I'll try to post it yet today. I'm still messing around with it. -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Hauppage hvr-950q au0828 transfer problem affecting audio and perhaps video
On Thu, Dec 3, 2009 at 11:00 PM, John S Gruber johnsgru...@gmail.com wrote: I have problems with my audio that I've tracked down to the transfer of audio from the au0828 in my hvr-950Q. I spotted the following comment about green screen detection and I wonder if it might be related. drivers/media/video/au0828/au0828-video.c: /* Workaround for a bug in the au0828 hardware design that sometimes results in the colorspace being inverted */ The problem is that sound/usb/usbaudio.c assumes that each urb data field contains an integer number of audio frames (aka audio slots), in this case a integer number of left channel-right channel pairs. About 12 times a second for my device a urb doesn't. This causes a flutter noise with non-quiet audio that contains a difference between the channels. I found this by using audacity to look at wave forms and a usb trace to see the problematic urb's. I've confirmed by relaxing the constraint in sound/usb/usbaudio.c with a patch and can confirm that it clears up the audio. Is the code comment at the top related to my problem? More importantly, is there the possibility of setting up the transfer differently so that audio slots aren't split between urbs? From what I have read in the spec I believe the split of the audio slots between urb's is non- conformant. Therefore I think it would be a mistake to change the default behaviour of usbaudio.c since, as it is now,usbaudio.c won't swap channels in the case of dropped urbs. It would be optimal if the hvr-950q could be set up to conform by not splitting audio slots. I think the problem also occurs for video when blue will turn to pink for a flash until the top of frame resyncs things up--because of the corresponding swap of UY with VY. This seems to be related to how busy my system is and what usb slot I'm using on my laptop. Again I could see in a usb trace the urb's with data_lengths such that UY would be split from the corresponding VY. The video transfer is a straight byte copy so ordinarily this isn't a problem but would be if an abnormally sized urb were dropped and the device and host were to get out of sync regarding V and U. I also have caught an occasional odd number of bytes transferred in traces, which requires the drop of incomplete samples in usbaudio.c. I wonder if this is related to the green screen problem on video from the top comment. The easiest way to reproduce the audio problem is to use the composite video input but only hook up either the left or the right audio. With earphonesyou can hear the audio rapidly go from ear to ear. Thanks for those on the list for their hard work on getting devices such as this to work. I'd appreciate any answers, comments, corrections, or information. Hi John, I have actually actively debugging the au0828 audio this evening. The comment you referred to (which I wrote) has to do with the delivery of the UYVY data from the demodulator to the au0828 bridge, which can cause the start of the stream to be off-by-one (the pink/green you see is the colorspace inverted when the decoder loses sync). It is unrelated to audio. I'm working an issue now where the audio keeps dropping out. If you want to show me the code change you did to usbaudio.c, it might give me a better understand the issue. Cheers, Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Hauppage hvr-950q au0828 transfer problem affecting audio and perhaps video
On Thu, Dec 3, 2009 at 11:21 PM, Devin Heitmueller dheitmuel...@kernellabs.com wrote: On Thu, Dec 3, 2009 at 11:00 PM, John S Gruber johnsgru...@gmail.com wrote: I have problems with my audio that I've tracked down to the transfer of audio from the au0828 in my hvr-950Q. I spotted the following comment about green screen detection and I wonder if it might be related. drivers/media/video/au0828/au0828-video.c: /* Workaround for a bug in the au0828 hardware design that sometimes results in the colorspace being inverted */ The problem is that sound/usb/usbaudio.c assumes that each urb data field contains an integer number of audio frames (aka audio slots), in this case a integer number of left channel-right channel pairs. About 12 times a second for my device a urb doesn't. This causes a flutter noise with non-quiet audio that contains a difference between the channels. I found this by using audacity to look at wave forms and a usb trace to see the problematic urb's. I've confirmed by relaxing the constraint in sound/usb/usbaudio.c with a patch and can confirm that it clears up the audio. Is the code comment at the top related to my problem? More importantly, is there the possibility of setting up the transfer differently so that audio slots aren't split between urbs? From what I have read in the spec I believe the split of the audio slots between urb's is non- conformant. Therefore I think it would be a mistake to change the default behaviour of usbaudio.c since, as it is now,usbaudio.c won't swap channels in the case of dropped urbs. It would be optimal if the hvr-950q could be set up to conform by not splitting audio slots. I think the problem also occurs for video when blue will turn to pink for a flash until the top of frame resyncs things up--because of the corresponding swap of UY with VY. This seems to be related to how busy my system is and what usb slot I'm using on my laptop. Again I could see in a usb trace the urb's with data_lengths such that UY would be split from the corresponding VY. The video transfer is a straight byte copy so ordinarily this isn't a problem but would be if an abnormally sized urb were dropped and the device and host were to get out of sync regarding V and U. I also have caught an occasional odd number of bytes transferred in traces, which requires the drop of incomplete samples in usbaudio.c. I wonder if this is related to the green screen problem on video from the top comment. The easiest way to reproduce the audio problem is to use the composite video input but only hook up either the left or the right audio. With earphonesyou can hear the audio rapidly go from ear to ear. Thanks for those on the list for their hard work on getting devices such as this to work. I'd appreciate any answers, comments, corrections, or information. Hi John, I have actually actively debugging the au0828 audio this evening. The comment you referred to (which I wrote) has to do with the delivery of the UYVY data from the demodulator to the au0828 bridge, which can cause the start of the stream to be off-by-one (the pink/green you see is the colorspace inverted when the decoder loses sync). It is unrelated to audio. I'm working an issue now where the audio keeps dropping out. If you want to show me the code change you did to usbaudio.c, it might give me a better understand the issue. I am definitely seeing what you are saying with regards to the channel flipping back and forth. Do you know what size URBs are being delivered? If you've got a hacked up version of usbaudio.c, how about adding a printk() line which dumps out the URB size and send me a dump? Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
