In this thread http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=914949&Replies=24 JonnyRoy said, “ I know of no tool that will trim M2T files without re-rendering so it must be hard to do or someone would have done it.”
I always thought that Vegas smart rendered m2t files (HDV), meaning that the GOP(s) where a cut or cuts had been made would be re-rendered but the rest would be passed through unchanged. Certainly VideoRedo does just that. Did JR mean something else?
Also, Laurence said, “Theoretically, a smart-render of HDV and XDcam done at the 1440x1080 dimensions and a 25Mbps bitrate should look the same. That is to say, the bulk of the smart-render should be identical and there should be some second generation loss around the edit points and in to the next I-frame. (etc.) In actual practice, in an HDV smart-render, the degradation around the edit points and to the next i-frame is clearly visable, even to a strongly spectacled individual such as myself. “
I have only done limited testing, but I could not see any obvious degradation at the trims. Either my eyesight is worse than Laurences’s, or I don’t know what to look for (or more likely, both the above!). The nature of the scene may also be important.
I then took a HDV clip and trimmed a few frames off each end and smart rendered it out to a new clip. I then loaded the source and rendered clips into the Vegas timeline, with the source at the top and the rendered clip underneath, and aligned the latter to account for the trimmed frames. I then used the compositing tool to give the difference between the two clips.
Generally the difference view was very dark, but by straining my eyes I could see some noise in the re-rendered GOPs. What surprised me was that I could also see noise from time to time during the “unrendered” section!!!
I then rendered the original clip to a SD MPEG2 file and repeated the exercise with it. Once again I could see noise in the re-rendered GOPs but the noise during the “unrendered” portion was quite blocky.
I trimmed the HDV and SD clips with VideoRedo and in both cases I could see difference noise in the GOP sections, and in both cases no noise during the unrendered sections. (For some reason the HDV clip trimmed with VideoRedo was two frames shorter at the start, but that is another matter.)
So VideoRedo does smart render and Vegas does not, despite the “No recompression required” message and the rapid processing.
I always thought that Vegas smart rendered m2t files (HDV), meaning that the GOP(s) where a cut or cuts had been made would be re-rendered but the rest would be passed through unchanged. Certainly VideoRedo does just that. Did JR mean something else?
Also, Laurence said, “Theoretically, a smart-render of HDV and XDcam done at the 1440x1080 dimensions and a 25Mbps bitrate should look the same. That is to say, the bulk of the smart-render should be identical and there should be some second generation loss around the edit points and in to the next I-frame. (etc.) In actual practice, in an HDV smart-render, the degradation around the edit points and to the next i-frame is clearly visable, even to a strongly spectacled individual such as myself. “
I have only done limited testing, but I could not see any obvious degradation at the trims. Either my eyesight is worse than Laurences’s, or I don’t know what to look for (or more likely, both the above!). The nature of the scene may also be important.
I then took a HDV clip and trimmed a few frames off each end and smart rendered it out to a new clip. I then loaded the source and rendered clips into the Vegas timeline, with the source at the top and the rendered clip underneath, and aligned the latter to account for the trimmed frames. I then used the compositing tool to give the difference between the two clips.
Generally the difference view was very dark, but by straining my eyes I could see some noise in the re-rendered GOPs. What surprised me was that I could also see noise from time to time during the “unrendered” section!!!
I then rendered the original clip to a SD MPEG2 file and repeated the exercise with it. Once again I could see noise in the re-rendered GOPs but the noise during the “unrendered” portion was quite blocky.
I trimmed the HDV and SD clips with VideoRedo and in both cases I could see difference noise in the GOP sections, and in both cases no noise during the unrendered sections. (For some reason the HDV clip trimmed with VideoRedo was two frames shorter at the start, but that is another matter.)
So VideoRedo does smart render and Vegas does not, despite the “No recompression required” message and the rapid processing.