few questions on Pro X

v850tw wrote on 3/22/2017, 10:52 AM

I have been learning Pro X a few weeks now. I am thinking to buy this, but have a few issues I am uneasy with.

First... I am shooting on a gopro hero 4 with no problems. My second camera used most the time is a Panasonic HC-X920. This makes AVCHD files in .mts format. The footage looks great. When I finish a project and need to encode is where the problem begins. If there is any fast action, encoding to mp4 has problems. I think it is with the GOP structure. I have played around with various results from IBP, IBBP, IPP, and all I frames. Sometimes a mostly gray sky will have bad block artifacts on final encoding. If I export as a cineform avi, I get a beautiful final video, but the size is enormous which takes an eternity to upload to youtube. So... what's the deal? How can I encode to mp4 and have smooth non-jerky video? I have tried data rates over 35,000mbps, in auto GOP mode... every variation I can think of, but in a scene with lots of movement, there will be something going on with pixel blocks jerking around.

My other issue is in editing. Some times, every time I hit the spacebar to play on the timeline, the play head goes all the way to the beginning of the time line, no matter where the play head is in the video. I then have to reboot to fix this.

Another issue is, How when trimming the head of a clip, to get the rest of the clips to follow along? If I grab the head of a clip in the middle of many clips, and move it to the right, to shorten it, it will not snap to the left to fill the gap. I do have the tool set correctly (ripple edit) so everything to the right should follow... and it does if just moving a clip, but not trimming the head of a clip. What am I doing wrong?

There are other issues that I think are clunky, but if I could just get a clean export to mp4, I would be a happy camper and purchase the program. Oh... Not sure if it makes a difference, but my cam files are 1080P at the highest quality the cam goes.

Comments

johnebaker wrote on 3/22/2017, 4:16 PM

. . . . Sometimes a mostly gray sky will have bad block artifacts on final encoding . . .

This sounds like you are using a low bitrate which is strongly compressing the video.
. . . . If I export as a cineform avi, I get a beautiful final video, but the size is enormous . . . .

This supports the above, AVI file format is less compressed.
. . . . How can I encode to mp4 and have smooth non-jerky video . . . .

What framerate are the two video sources recording at and which mp4 export setting are you using?
. . . .every time I hit the spacebar to play on the timeline, the play head goes all the way to the beginning of the time line. . . .

In the Program settings, Playback tab do you have Spacebar stops at current playback position checked ?
. . . .How when trimming the head of a clip, to get the rest of the clips to follow along? . . .

Try positioning the timeline cursor at the trim position and use the Z key to trim the start, or U key the end, the other objects should then ripple along depending on whether you have set the ripple to Single - track ripple or Multi-track ripple

Note: under certain circumstances the auto ripple will not work or overlap other objects on other tracks.

HTH

John EB

v850tw wrote on 3/22/2017, 5:15 PM

Hi

. . . . Sometimes a mostly gray sky will have bad block artifacts on final encoding . . .

This sounds like you are using a low bitrate which is strongly compressing the video.
I was over 35,000mbps, as I said above. I was also using the BEST encode setting instead of balanced.

. . . . If I export as a cineform avi, I get a beautiful final video, but the size is enormous . . . .

This supports the above, AVI file format is less compressed.
Not in this case. I believe the cineform is not using a IBP gop structure which is prone to artifacts especially when the original file was a highly compressed AVCHD clip. A 14 minute .avi video was 24 gigs.

. . . . How can I encode to mp4 and have smooth non-jerky video . . . .

What framerate are the two video sources recording at and which mp4 export setting are you using?
The cam footage was 1080P 59.97 as was the timeline as was the encoding for MP4 at FULL HD 59.97 Most the video looks great, except when there is a fair amount of motion.

. . . .every time I hit the spacebar to play on the timeline, the play head goes all the way to the beginning of the time line. . . .

In the Program settings, Playback tab do you have Spacebar stops at current playback position checked ?
I just looked... YES... it is checked.

. . . .How when trimming the head of a clip, to get the rest of the clips to follow along? . . .

Try positioning the timeline cursor at the trim position and use the Z key to trim the start, or U key the end, the other objects should then ripple along depending on whether you have set the ripple to Single - track ripple or Multi-track ripple
It took a few tries to understand what you were saying and I finally got it, to just place the playhead where I wanted to trim to and hit the Z or U key. Nice.... BUT... and, I can survive with this, but it is nice at times to drag - trim live, to get it where I want. I can do this with the tail end of a clip and the rest follow. But anyway... thanks for that.
Note: under certain circumstances the auto ripple will not work or overlap other objects on other tracks.

I think one of the reasons technology has moved from AVCHD cam files to mp4 files is because the AVCHD files are too compressed. Some other editors like Lightworks, decompresses them for editing and encodes from those decompressed files. Even gopro decompresses their files. BlackMagic's editor Davinchi, decompresses, or transcribes problem files. But, Davinchi can't touch an AVCHD file. 😩
I just happened to buy this cam, three year old technology because the price was right from B&H. It is a three chip cam which has very nice color. Thanks for your help.
If I can't figure out the encoding, I will have to go PowerDirector because it had no trouble encoding high action AVCHD's.

HTH

John EB

johnebaker wrote on 3/23/2017, 2:31 AM

Thanks for the reply.

. . . . The cam footage was 1080P 59.97 as was the timeline as was the encoding for MP4 at FULL HD 59.97 Most the video looks great, except when there is a fair amount of motion. . . . .

I did suspect one of the cameras was at a different frame rate or recording 1080i video, however as both are in 1080p and the same frame rate, I think this may be a result of one of the limitations with progressive video and fast motion. Does the original source video play smoothly when played in Windows Media Player?

. . . . moved from AVCHD cam files to mp4 files is because the AVCHD files are too compressed . . . .

MP4 is more compressed than AVCHD, AVCHD gives a higher quality and bigger file sizes. The reason why MP4 is more common than AVCHD is compatibility with playback devices, MP4 is the more universal format.

HTH

John EB

v850tw wrote on 3/23/2017, 8:14 AM

Thanks for your answers.... I am not sure... but AVCHD cam files seems to have a limitation of 28000mbps where as, MP4 goes way up there. All the 4k and lower, are mp4 today. Anyway.... oh yes.... When I play back from the cam direct to the TV, it is smooth. It is smooth in the computer also. It is just the re-encoding. As I play with the GOP structure.... I can help one thing but not the other. AVI is not a GOP structure... as far as I know. That is why it is larger. But... A good encoder lets you set it to create a new I frame when it sees much movement change. This way it is not borrowing older frame information to represent new movement. A shorter GOP does help. I just uploaded a video to youtube that is under ten minutes and it was 20 gigs. It plays smooth. It was just, a long upload.

johnebaker wrote on 3/23/2017, 11:43 AM

Altering the GOP structure can introduce more problems then it fixes - all the presets in MEP are optimised for the appropriate output preset.

. . . . I just uploaded a video to youtube that is under ten minutes and it was 20 gigs. It plays smooth . . . .

If you are preparing video for Youtube then whatever settings you use, Youtube automatically re-encodes the video, it also will re-encode to various resolutions down to 240p for delivery over different Internet connection speeds.

. . . . AVI is not a GOP structure . . . .

AVI is a container file format not a video format - it can contain video and audio in a variety of codecs.

John EB

v850tw wrote on 3/24/2017, 7:23 PM

If changing a default GOP structure will only make things worse... then why has this been made available to us to change? AVI is does not use a GOP structure of mpeg. Each frame in avi, as far as I know... stands by itself. I think that is why the size is much bigger, because it can not benefit from some frames borrowing from others.

Scenestealer wrote on 3/24/2017, 8:18 PM

I have a very similar earlier model Panasonic camera to yours, an SD900 and have no complaints about the encoded video when using the HQ 50P (PAL) export 28,000kbps AVCHD Transport Stream template in ProX, regardless of the content in the footage.

As John has suggested, it is better not to change the parameters in the Advanced Encoder Settings as this can create less than ideal results. The 50P HQ template gives the file very similar frame data to the camera original and the only thing I have changed in the past is pushing the max bit rate to 36Mbps and average to 32Mbps, where I was seeing a slight loss of detail in dark, low contrast areas. I do not bother doing this anymore because Magix have tweaked the template over the years to the point that I can not see the difference. As your NTSC 60P Frame rate is 20% higher than my 50P PAL Frame Rate, it may be beneficial for you to change the Bit rate of the Template to something higher to give more bits to each frame.

AVCHD cam files seems to have a limitation of 28000k(m)bps

This is a standard (AVCHD2), not a limitation.

. . . . AVI is not a GOP structure . . . .

By the size you quote for the output file you must be referring to "Uncompressed AVI" which indeed has no GOP structure. Cineform is a lowly compressed or uncompressed "Intermediate" codec that is designed to be easy to edit.

It is not that AVCHD is necessarily more compressed than MP4, but that the compression is more complex requiring more system resources to encode and decode.

.every time I hit the spacebar to play on the timeline, the play head goes all the way to the beginning of the time line. . . .

This is a well documented bug that can creep in to a project that can sometimes be overcome by clicking the double headed arrow at the bottom right of the timeline. The other solution is to copy and past all the objects in the timeline into a renamed project.

A shorter GOP does help

Only if you increase the Bit Rate at the same time as there are fewer highly compressed B and P frames and more lowly compressed I frames for the same amount of frames and bandwidth, which means fewer bits per pixel for each detailed I frame which becomes more compressed.

v850tw wrote on 4/2/2017, 11:15 AM

I found a solution that seems to work well on the few projects that have lots of action - movement. I export as .avi, which is not lossless (uncompressed) but it is not a GOP structure like MP4. The link below exported in .avi was 25gigs, but almost twice that exported as prores... So, .avi can not be uncompressed. There are actually a variety of quality settings for .avi, that include two higher "film scan" settings that really make huge files (I tried them). Then, I loaded this file in gopro studio and exported as mp4. It did not take a long time and the result was a nice video with no encoding artifacts. I tried loading the same .avi back in to Magix to export in mp4, and it is taking soooo long. A file that gopro did in less than an hour has been crunching in Magix three hours now, and has two hours to go. I am happy with the fix. Many projects I have tried, that don't have too much action don't require this solution. I have tried as you said, to use the AVCHD preset for 59.97p at a higher rate, but there was still some very jumpy pixel blocks in some action areas where the camera was panning too fast or the action was really moving. I suspect it was a 60 frame GOP. This is only new frame information every second. I set it to auto, and it did help a little. Over all, I am getting happier with Magix and my consumer camera. Here is a link to a video that I had to export as .avi before uploading to youtube. If you look closely, the over ocean shots with sailboat still has some strange artifacts going on in the gray sky above the ocean... but it is slight, and not like it was in mp4 exporting.