When Transcoding fails, there can be several possible problems. Here are two of those:
Assets that are not working well in Premiere.
Gaps in the Video portion of the Timeline.
Now, there are some differences in the way that PrE and PrPro Transcode a Timeline. In PrE, the program will use a 2-pass VBR (Variable Bit-Rate), so 100% of the Transcode will be both passes. Because of this, if the program reports 75% completion, then it’s failing at ~ the half-way point in the second pass. One needs to do a bit of math. In PrPro, one can set the Transcoding, so they may, or may not need to do that same math.
Now, let’s say that the Transcoding stops at 75%, and 2-pass VBR was used. That equals about half-way through the Timeline, and on the second pass. That is where one should start looking, and looking closely at the Assets around that point. Does one have overly-large still images there? If so, then this ARTICLE will give some tips on how to handle those. Does one have an odd Video CODEC in a Clip at that point? Is there something in one of the Assets, that differs from those around it? If so, correct that.
Now, with Video, gaps can cause all sorts of issues with Transcoding. One can experience this in several ways. One common error is “Failure to return Frame,” but another is “Transcode failed,” or just a crash/hang, and there might be no real error message.
The finding of the gap can be tough. A 1-Frame gap can cause such a problem. To locate a gap, I recommend that first, one zooms into the Timeline, at about the point of failure, and look closely. If no gap is seen, I recommend that they then use a method, that is as much by “feel,” as it is by sight. Move the CTI (Current Time Indicator) to before that general area of the Timeline, which has been zoomed in to the max, and use the PageUP (or PageDN, depending on the direction) to step through the Timeline, Clip by Clip (note: this will step by ALL Clips, both Audio & Video, so observe closely). The CTI will move directly to the beginning of the next Clip. If the CTI seems to “pause,” or “hiccup,” there is likely a gap at that point. Check out that point very closely. In the Program Monitor, at that point, there will be a black “flash,” but it might go by very, very quickly, in 1/30th +/- of a second.
How one handles a gap, will depend on the Clips on either side, perhaps any underlying Audio, or what one wishes to actually happen at that exact point.
In PrPro, one trick is to add Transparent Video to a higher Video Track, and extend that to cover any/all gaps. Unfortunately, that will likely get a good Transcode, BUT, any black “flash” will still occur, so it should only be used for testing purposes, unless one wants a 1-2 Frame black “flash” to appear there.
In PrE, there is no Transparent Video, but it has something close, a Title. Just create a Title, and if you used a Template, remove all Text and all Shapes, so that you have what appears to be a black Frame in Titler. It is really Transparent. Use it, just like Transparent Video, to test for gaps.
Some will contend that a gap in the video is not an issue. I had one Project, that I inherited, and it had been Transcoded successfully by the original editor. In the 8 hours, it had over 900 gaps. I went about fixing all of those, though I had yet to do my re-edit Transcode. However, I have seen a 1-Frame gap kill the Transcode, and when rectified, all worked well. Why? I have no idea. I would assume that a gap is a gap. Still, I always remove them.
PrE has the ability to Close Gaps, BUT if there is underlying Audio, that spans the gap, then the gaps will NOT be closed.
Ann Bens outlined a simple method for closing gaps, or at least finding them, in PrPro. Her method is outlined HERE.
Often, one will start Transcoding, and then go and do something else. When they return, the progress screen is gone, and all they have is an error message. There is usually no info in that error message, as to where in the Timeline, things failed. One trick is to set up a video camera, focused on the progress screen, and record that. If there is a failure, one only has to go back to the video in the camera, and find the point, where the progress screen stopped. Pause the tape, or playback, and make note of either the %, or in PrPro, the Frame, where Transcoding quit. That is the general area to begin checking the Timeline.
Also note that there could well be other problems in the Timeline, and Transcoding halted on the first. One might have to repeat the search for problems, as there could well be more, further along the Timeline.
Hope that this helps someone,