TROUBLESHOOTING

"Your professors are wrong. Every question is a stupid question." -- gcc version 2.95.2

Most of the problems userse encounter are due to operating system limitations. Since Linux was designed for embedded systems, video applications tend to go against the grain but there are ways around the compacted nature of the operating system.

RECORDING

PROBLEM: THE DC10/BUZ/ZORAN/LML33/MJPEG ETC DRIVER LOCKS UP

The following derivatives of the dc10/buz/zoran/lml33/mjpeg etc driver need to be patched:

Version 0.6
Version 0.7

Comment out the following segment in dc10.c:

/*
 * 			if (zr->codec_mode != BUZ_MODE_IDLE) {
 * 				if (v.norm != zr->params.norm || v.channel != zr->params.input) {
 * 					printk(KERN_ERR "%s: VIDIOCSCHAN called while the card in capture/playback mode\n", zr->name);
 * 					return -EINVAL;
 * 				} else {
 * 					printk(BUZ_WARNING
 * 					       "%s: Warning: VIDIOCSCHAN called while the card in capture/playback mode\n", zr->name);
 * 				}
 * 			}
 */

PROBLEM: THE BTTV DRIVER LOCKS UP

The following derivatives of the bttv driver need to be replaced:

Kernel 2.2.* Video4Linux 1

Replace the bttv.c file with the patched version of bttv.c at http://heroinewarrior.com/bcast2000.html to defeat most of the bttv lockups. Overwrite the copy of bttv.c in /usr/src/linux/drivers/char and recompile the kernel. This driver is omitted from the shipped kernel for various pedantic reasons.

TRYING TO RECORD FROM AN UNCOMPRESSED VIDEO SOURCE CRASHES IT

Reason 1: Issue echo "0x7fffffff">/proc/sys/kernel/shmmax to increase the amount of shared memory the operating system can allocate.

Reason 2: There are separate configuration settings for audio and video recording. If you select video4linux for video capture the audio may still attempt to capture from firewire. Be sure to set the preferences->audio in.

RECORDING SPITS OUT FRAMES AND THEN PAUSES AND THEN SPITS OUT FRAMES

Reason 1: Your using software compression, attempting a higher framerate and more compression than your computer is capable of. Lower the frame rate or compression quality or use a less demanding codec.

Reason 2: Your hard drive is too slow. Lower the framerate or use a smaller format.

Reason 3: Your hard drive is benchmarked fast enough but is still responding too slowly. Use the following script to flush the operating system's cache every second, ensuring more consistant hard drive performance.

#!/bin/sh

while : ; do
	sync
	sleep 1
done

RECORDING 29.97fps DROPS FRAMES IN LINUX BUT WORKS FINE IN WIN95

Reason 1: You're using a derivative of the bttv driver which only allows 2 frames of buffering. The following derivatives defeat this problem:

Linux 2.4.* Video4Linux 1
Linux 2.2.* Video4Linux 2

Load the Linux 2.4.0 Video4Linux 1 derivative with "gbuffers=32 gbufsize=0x100000" to allocate 32 frame buffers instead of 2.

In Linux 2.2 install the Video4linux 2 derivative of the bttv driver.

MY BT8** CARD ISN'T CAPTURING D-1 RESOLUTION

The following derivatives of the bttv driver need to be hacked to support D-1 resolution:

Linux 2.2.* Video4Linux 2

You need to hack btv/bttv-v4l2.c to support it. Change all the occurances of 640 in btv/bttv-v4l2.c to 720.

THE LML33 DRIVER PRODUCES GARBAGE ON THE LEFT SIDE OF THE FRAME OR DOESN'T FILL THE ENTIRE FRAME

The LML33 supports only 720x480 resolution. Be sure to set the frame size accordingly in File->new before you start to record.

RECORDING FROM MY FIREWIRE CAMCORDER DOESN'T WORK!

Reason 1: The operating system failed to detect the device when you loaded the firewire modules, which is normal. Linux1394 was mainly designed for computer networking not camcorders. You need to cancel recording and reload the modules until it works.

Reason 2: You power cycled your camcorder with the firewire modules loaded and the operating system failed to redetect the device. You need to cancel the recording and reload the firewire modules.

Reason 3: You plugged in your camcorder after the firewire modules loaded and the device was never detected. You need to cancel the recording and reload the firewire modules every time you power cycle the camera.

Reason 4: You're not playing any video on the camcorder. You need either live video or tape playback for the firewire system to work. Once you start playing video, you'll automatically get a picture.

Reason 5: The audio must be set to 16 bit. 12 bit audio can't be detected.

Reason 6: Maybe you don't really like short haired blonds.