ConnectHD 3.3 capturing at DVinfo.net

Matti Remonen · December 15th, 2006, 12:54 PM

Hi,
in Vegas forum there was discussion why Vegas VidCap is muting the sound a few frames before video ends. I started to investigate the matter and at the same time I'm evaluating ConnectHD.

Using the same material I made following captures:

HDVSplit -> m2t
Vegas VidCap -> m2t
Cineform HDLink -> m2t
Cineform HDLink -> AVI (CFHD)

Material is PAL 25 fps.

I captured the same tape with the same equipment (HVR-M15E) except with HDVSplit where HVR-A1E was used.

It seems that for some reason CFHD-material (scenes) are always a few frames (up to 20) shorter than m2t -material, i.e. the scene ends prematurely. I do have screenshots to prove this but for some reason I cannot upload anything here.

Also, what is possibly a bit more worrying, the audio is lagging approx. two frames when compared to m2t material. On the other hand the m2t material captured by HDLink is exactly identical to m2t-files captured by those other two apps.

Is these features really by design or by error? Has it always been like this? This is my first evaluation of ConnectHD, so I cannot refer to any older material.

Also my favorite comes last (no-one has yet answered this): will there be a possibility to name the scenes in HDLink so that the scene name will include date and time of shooting. Also for CFHD.

Thanks and BR,

MRe

Edit: I just made one more test for the road. I converted material captured with HDVSplit using HDLink to CFHD. Some of the converted scenes are longer than the source material and start before (i.e. from earlier frame) than the source. Go figure. This HDV-thing is over my head.

And yes, this way I can retain my so precious file naming scheme.

I'll rest my case and go to bed... G'night.

David Newman · December 15th, 2006, 03:59 PM

MPEG transport streams are complex beasts. Due to the GOP structure and the scene detection algorithm you can lose a couple frame off the ends -- never anything significant. As for audio sync the AVIs are likely to be correct, and the way your NLE displays M2T waveforms likely wrong. Audio and Video packets are synced up before they are wrapped into an AVI, we use presentation time information stored with the two streams to obtain an accurate sync. Within the M2T file itself there can be drift between the streams, as the audio datarate is constant yet the video datarate varies with the size of the I,P & B frames, so the first video sample and audio sample within an M2T don't usual have the same presentation time, so using a waveform my not be accurate when viewing an M2T (that will depend on the host NLE.)

Matti Remonen · December 16th, 2006, 09:01 AM

Thanks David. I'm starting to realize that there is more in the HDV than meets the eye.

I take your word for this and I start to believe that the AVI's created by ConnectHD are correct. After all, you are the ones in this business, not me.

Anyway, what about the date and time info from the original material as the name for scene? I won't rest before this has been settled ;)

December 15th, 2006, 12:54 PM	#1
Matti Remonen Regular Crew Join Date: Oct 2006 Location: Helsinki, Finland Posts: 54	ConnectHD 3.3 capturing Hi, in Vegas forum there was discussion why Vegas VidCap is muting the sound a few frames before video ends. I started to investigate the matter and at the same time I'm evaluating ConnectHD. Using the same material I made following captures: HDVSplit -> m2t Vegas VidCap -> m2t Cineform HDLink -> m2t Cineform HDLink -> AVI (CFHD) Material is PAL 25 fps. I captured the same tape with the same equipment (HVR-M15E) except with HDVSplit where HVR-A1E was used. It seems that for some reason CFHD-material (scenes) are always a few frames (up to 20) shorter than m2t -material, i.e. the scene ends prematurely. I do have screenshots to prove this but for some reason I cannot upload anything here. Also, what is possibly a bit more worrying, the audio is lagging approx. two frames when compared to m2t material. On the other hand the m2t material captured by HDLink is exactly identical to m2t-files captured by those other two apps. Is these features really by design or by error? Has it always been like this? This is my first evaluation of ConnectHD, so I cannot refer to any older material. Also my favorite comes last (no-one has yet answered this): will there be a possibility to name the scenes in HDLink so that the scene name will include date and time of shooting. Also for CFHD. Thanks and BR, MRe Edit: I just made one more test for the road. I converted material captured with HDVSplit using HDLink to CFHD. Some of the converted scenes are longer than the source material and start before (i.e. from earlier frame) than the source. Go figure. This HDV-thing is over my head. And yes, this way I can retain my so precious file naming scheme. I'll rest my case and go to bed... G'night. Last edited by Matti Remonen; December 15th, 2006 at 02:36 PM.

December 15th, 2006, 03:59 PM	#2
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	MPEG transport streams are complex beasts. Due to the GOP structure and the scene detection algorithm you can lose a couple frame off the ends -- never anything significant. As for audio sync the AVIs are likely to be correct, and the way your NLE displays M2T waveforms likely wrong. Audio and Video packets are synced up before they are wrapped into an AVI, we use presentation time information stored with the two streams to obtain an accurate sync. Within the M2T file itself there can be drift between the streams, as the audio datarate is constant yet the video datarate varies with the size of the I,P & B frames, so the first video sample and audio sample within an M2T don't usual have the same presentation time, so using a waveform my not be accurate when viewing an M2T (that will depend on the host NLE.) __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

December 16th, 2006, 09:01 AM	#3
Matti Remonen Regular Crew Join Date: Oct 2006 Location: Helsinki, Finland Posts: 54	Thanks David. I'm starting to realize that there is more in the HDV than meets the eye. I take your word for this and I start to believe that the AVI's created by ConnectHD are correct. After all, you are the ones in this business, not me. Anyway, what about the date and time info from the original material as the name for scene? I won't rest before this has been settled ;)