# Encoding/viewing NTSC signal? **URL:** \ **Category:** Uncategorized\ **Created:** [February 15, 2008, 12:20pm UTC](https://psychtoolbox.discourse.group/t/encoding-viewing-ntsc-signal/1941 "2008-02-15T12:20:17Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![kjmacken](https://avatars.discourse-cdn.com/v4/letter/k/839c29/32.png) [@kjmacken](https://psychtoolbox.discourse.group/u/kjmacken)\ **Post date:** [February 15, 2008, 12:20pm UTC](https://psychtoolbox.discourse.group/t/encoding-viewing-ntsc-signal/1941/1 "2008-02-15T12:20:17Z")
Hi there, I am trying to extract a video feed from an NTSC device. I have an NTSC video signal from a component RCA cable into an analogue to digital convertor which is then connected to an iMac via firewire. I get a digital video signal without issue through programs like iMovie and other media applications. I have been playing with the demos in PsychVideoCapture without success. Trying the PsychCamSettings.m function, I get the following output to screen: PTB-INFO: OpenGL-Renderer is ATI Technologies Inc. :: ATI Radeon HD 2400 XT OpenGL Engine :: 2.0 ATI-1.5.24 PTB-INFO: Renderer has 128 MB of VRAM and a maximum 119 MB of texture memory. PTB-Info: VBL startline = 1050 , VBL Endline = -1 PTB-Info: Beamposition queries unsupported on this system. Will try to use kernel-level vbl interrupts as fallback. PTB-Info: Measured monitor refresh interval from VBLsync = 16.665254 ms [60.005085 Hz]. (50 valid samples taken, stddev=0.047283 ms.) PTB-Info: Small deviations between reported values are normal and no reason to worry. PTB-INFO: Using OpenGL GL\_TEXTURE\_RECTANGLE\_EXT extension for efficient high-performance texture mapping... PTB-WARNING: Video capture device didn't accept new capture area. Reverting to full hardware capture area, PTB-WARNING: Trying to only process specified ROI by restricting conversion to ROI in software... PTB-WARNING: Video capture device didn't accept new capture area. Reverting to full area... and the process hangs here. Trying to poll for the device name/vendor/model, I get unknown as a reply. So, it seems that perhaps the analogue-digital convertor is not recognized, or that the signal is not being translated. I've played with the grabber's rect size to conform to an NTSC signal dimension, but that doesn't seem to help. Are there only specific firewire ADV devices that this will work for? I have no issues getting a video feed from the built-in iSight camera. Other important information: Matlab Version R2007b (7.5.0.338) > \>\> PsychtoolboxVersion ans = 3.0.8 - Flavor: trunk - Corresponds to SVN Revision 985 but is \*locally modified\* ! For more info visit: [http://svn.berlios.de/wsvn/osxptb/?rev=985&sc=0](http://svn.berlios.de/wsvn/osxptb/?rev=985&sc=0) I tried the latest trunk version, no joy with the latest beta downloaded last night. Computer specs: iMac OS 10.5.2 2 GHz Intel Core 2 Duo 2 GB RAM ATI Radeon HD 2400 XT display device 128 MB onboard memory I've looked into other methods of capturing the video feed, and there is the Matlab Image acquisition toolbox, but that seems to be windows only, therefore is not ideal. So, my two main questions are (1) is there a method to capture this signal through matlab and the PTB, (2) is there a specific analogue - video convertor that is known to work for Matlab+PTB+OS x? Any help/advice would be greatly appreciated! Thanks, Kevin MacKenzie School of Psychology, Bangor University, Wales, UK Centre for Vision Research, York University, Canada -- Gall y neges e-bost hon, ac unrhyw atodiadau a anfonwyd gyda hi, gynnwys deunydd cyfrinachol ac wedi eu bwriadu i'w defnyddio'n unig gan y sawl y cawsant eu cyfeirio ato (atynt). Os ydych wedi derbyn y neges e-bost hon trwy gamgymeriad, rhowch wybod i'r anfonwr ar unwaith a dil�wch y neges. Os na fwriadwyd anfon y neges atoch chi, rhaid i chi beidio � defnyddio, cadw neu ddatgelu unrhyw wybodaeth a gynhwysir ynddi. Mae unrhyw farn neu safbwynt yn eiddo i'r sawl a'i hanfonodd yn unig ac nid yw o anghenraid yn cynrychioli barn Prifysgol Bangor. Nid yw Prifysgol Bangor yn gwarantu bod y neges e-bost hon neu unrhyw atodiadau yn rhydd rhag firysau neu 100% yn ddiogel. Oni bai fod hyn wedi ei ddatgan yn uniongyrchol yn nhestun yr e-bost, nid bwriad y neges e-bost hon yw ffurfio contract rhwymol - mae rhestr o lofnodwyr awdurdodedig ar gael o Swyddfa Cyllid Prifysgol Bangor. www.bangor.ac.uk This email and any attachments may contain confidential material and is solely for the use of the intended recipient(s). If you have received this email in error, please notify the sender immediately and delete this email. If you are not the intended recipient(s), you must not use, retain or disclose any information contained in this email. Any views or opinions are solely those of the sender and do not necessarily represent those of the Bangor University. Bangor University does not guarantee that this email or any attachments are free from viruses or 100% secure. Unless expressly stated in the body of the text of the email, this email is not intended to form a binding contract - a list of authorised signatories is available from the Bangor University Finance Office. www.bangor.ac.uk ---
**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\ **Post date:** [February 18, 2008, 7:44pm UTC](https://psychtoolbox.discourse.group/t/encoding-viewing-ntsc-signal/1941/2 "2008-02-18T19:44:20Z")
PTB's Quicktime capture engine is agnostic to the type of video capture device connected. It simply asks Quicktime for the 1st (2nd, ...) attached device and performs a standard setup procedure, hoping that Quicktime knows how what it is doing. If a specific exotic device would need unusual treatment - or have unusual bugs in its capture driver - we couldn't handle it. What device/model do you use? I've tested the QT engine with the built-in iSight, some Firewire consumer DV video camera (some Sony DSC something), and two Firewire machine vision cameras (Unibrain Fire-i and Basler 602bc) - the limited test set i had. Quicktimes capture engine is sometimes quite fragile and buggy in my experience - always good for some surprise, so i wouldn't be too surprised if you hit some corner case. It often has problems choosing the spec'd 'rect'angle or framerate for example. Have you tried different framerates, e.g., 30 and 60 fps, or a rectangle half the height, e.g., 240 instead 480? Maybe something funky is going on with interlaced video material... Did you add some debug output to the test scripts, e.g., VideoCaptureDemo to find out at which command exactly matlab is hanging? You can also do a Screen('Preference', 'Verbosity', 10); to get a bit more debug output. Another option would be to test the new Firewire capture engine iff your converter box is a firewire connected IIDC compliant device: Screen('Preference', 'DefaultVideocaptureEngine', 1); that won't work with consumer equipment though. -mario > --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), "franswcornelissen" \ wrote: > \> > \> Kevin, > \> > \> > \> We've been using the Canopus ADVC-110 converter on a macbook pro and powerbook > G4 > \> to record video. > \> I don't recall there were any complications and it did work okay with the recording > \> demo's of PTB. > \> > \> gr. > \> frans > \> > \> > \> > \> > \> > \> --- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), Kevin Mackenzie \ wrote: > \> \> > \> \> Hi there, > \> \> > \> \> I am trying to extract a video feed from an NTSC device. I have an > \> \> NTSC video signal from a component RCA cable into an analogue to > \> \> digital convertor which is then connected to an iMac via firewire. > \> \> > \> \> I get a digital video signal without issue through programs like > \> \> iMovie and other media applications. I have been playing with the > \> \> demos in PsychVideoCapture without success. > \> \> > \> \> Trying the PsychCamSettings.m function, I get the following output to > \> \> screen: > \> \> > \> \> PTB-INFO: OpenGL-Renderer is ATI Technologies Inc. :: ATI Radeon HD > \> \> 2400 XT OpenGL Engine :: 2.0 ATI-1.5.24 > \> \> PTB-INFO: Renderer has 128 MB of VRAM and a maximum 119 MB of texture > \> \> memory. > \> \> PTB-Info: VBL startline = 1050 , VBL Endline = -1 > \> \> PTB-Info: Beamposition queries unsupported on this system. Will try to > \> \> use kernel-level vbl interrupts as fallback. > \> \> PTB-Info: Measured monitor refresh interval from VBLsync = 16.665254 > \> \> ms [60.005085 Hz]. (50 valid samples taken, stddev=0.047283 ms.) > \> \> PTB-Info: Small deviations between reported values are normal and no > \> \> reason to worry. > \> \> PTB-INFO: Using OpenGL GL\_TEXTURE\_RECTANGLE\_EXT extension for > \> \> efficient high-performance texture mapping... > \> \> PTB-WARNING: Video capture device didn't accept new capture area. > \> \> Reverting to full hardware capture area, > \> \> PTB-WARNING: Trying to only process specified ROI by restricting > \> \> conversion to ROI in software... > \> \> PTB-WARNING: Video capture device didn't accept new capture area. > \> \> Reverting to full area... > \> \> > \> \> > \> \> and the process hangs here. > \> \> > \> \> Trying to poll for the device name/vendor/model, I get unknown as a > \> \> reply. So, it seems that perhaps the analogue-digital convertor is > \> \> not recognized, or that the signal is not being translated. I've > \> \> played with the grabber's rect size to conform to an NTSC signal > \> \> dimension, but that doesn't seem to help. > \> \> > \> \> Are there only specific firewire ADV devices that this will work for? > \> \> I have no issues getting a video feed from the built-in iSight camera. > \> \> > \> \> Other important information: > \> \> Matlab Version R2007b (7.5.0.338) > \> \> \>\> PsychtoolboxVersion > \> \> ans = > \> \> 3.0.8 - Flavor: trunk - Corresponds to SVN Revision 985 but is > \> \> \*locally modified\* ! > \> \> For more info visit: > \> \> [http://svn.berlios.de/wsvn/osxptb/?rev=985&sc=0](http://svn.berlios.de/wsvn/osxptb/?rev=985&sc=0) > \> \> > \> \> I tried the latest trunk version, no joy with the latest beta > \> \> downloaded last night. > \> \> > \> \> Computer specs: > \> \> iMac OS 10.5.2 > \> \> 2 GHz Intel Core 2 Duo > \> \> 2 GB RAM > \> \> ATI Radeon HD 2400 XT display device 128 MB onboard memory > \> \> > \> \> I've looked into other methods of capturing the video feed, and there > \> \> is the Matlab Image acquisition toolbox, but that seems to be windows > \> \> only, therefore is not ideal. So, my two main questions are (1) is > \> \> there a method to capture this signal through matlab and the PTB, (2) > \> \> is there a specific analogue - video convertor that is known to work > \> \> for Matlab+PTB+OS x? Any help/advice would be greatly appreciated! > \> \> > \> \> Thanks, > \> \> > \> \> Kevin MacKenzie > \> \> School of Psychology, Bangor University, Wales, UK > \> \> Centre for Vision Research, York University, Canada > \> \> > \> \> > \> \> -- > \> \> Gall y neges e-bost hon, ac unrhyw atodiadau a anfonwyd gyda hi, > \> \> gynnwys deunydd cyfrinachol ac wedi eu bwriadu i'w defnyddio'n unig > \> \> gan y sawl y cawsant eu cyfeirio ato (atynt). Os ydych wedi derbyn y > \> \> neges e-bost hon trwy gamgymeriad, rhowch wybod i'r anfonwr ar > \> \> unwaith a dilëwch y neges. Os na fwriadwyd anfon y neges atoch chi, > \> \> rhaid i chi beidio â defnyddio, cadw neu ddatgelu unrhyw wybodaeth a > \> \> gynhwysir ynddi. Mae unrhyw farn neu safbwynt yn eiddo i'r sawl a'i > \> \> hanfonodd yn unig ac nid yw o anghenraid yn cynrychioli barn > \> \> Prifysgol Bangor. Nid yw Prifysgol Bangor yn gwarantu > \> \> bod y neges e-bost hon neu unrhyw atodiadau yn rhydd rhag firysau neu > \> \> 100% yn ddiogel. Oni bai fod hyn wedi ei ddatgan yn uniongyrchol yn > \> \> nhestun yr e-bost, nid bwriad y neges e-bost hon yw ffurfio contract > \> \> rhwymol - mae rhestr o lofnodwyr awdurdodedig ar gael o Swyddfa > \> \> Cyllid Prifysgol Bangor. www.bangor.ac.uk > \> \> > \> \> This email and any attachments may contain confidential material and > \> \> is solely for the use of the intended recipient(s). If you have > \> \> received this email in error, please notify the sender immediately > \> \> and delete this email. If you are not the intended recipient(s), you > \> \> must not use, retain or disclose any information contained in this > \> \> email. Any views or opinions are solely those of the sender and do > \> \> not necessarily represent those of the Bangor University. > \> \> Bangor University does not guarantee that this email or > \> \> any attachments are free from viruses or 100% secure. Unless > \> \> expressly stated in the body of the text of the email, this email is > \> \> not intended to form a binding contract - a list of authorised > \> \> signatories is available from the Bangor University Finance > \> \> Office. www.bangor.ac.uk > \> \> > \>