Joining MP4 files

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musicvid10 wrote on 11/28/2012, 8:48 AM
There is nothing sacred about the AVCHD format. It is another transport stream. Nothing else.
Most HD is AVC. Whether it is wrapped as mts, mov, mp4, ts is of little consequence for AVC decoders. The mts/m2ts extension alone does not make it any different or behave any different than any other Transport Stream.

It is

You've acknowledged that your method did not work for the OP's files. Now you are passing that off to the fact that it was not wrapped as AVCHD? In what world does that make any sense? It was you who said files are files.

On the other hand, external TS intake applications are designed to deal with most situations, making it better than a hit-or-miss proposition, such as you are promoting. Certainly, index and stream error correction is a huge consideration when dealing with transport streams in general, even if a particular one sneaks through unscathed. The definition of Transport Streams is that they contain errors. Typically, these would occur more often at break points, and mess up the stream until (or unless) it finds a new reference frame. That's their nature. That's why it's important. Players are trained to find and fudge those errors. Nonlinear editors are not. Concatenation does not put the toothpaste back in the tube. Bet you didn't know that.

Eagerly awaiting the results of your trials, Peter.

I apologize unconditionally for the part I played in allowing this thread to be dragged so far off topic.
Done.
R0cky wrote on 11/28/2012, 3:32 PM
just use device explorer to import them. It will join them correctly.

rocky
PeterDuke wrote on 11/29/2012, 12:23 AM
OK musicvid, I too feel uncomfortable about hijacking a thread, so let's see if we can put this to rest.

>>> "There is nothing sacred about the AVCHD format. It is another transport stream. Nothing else."

AVCHD is a standard (now set of standards) produced jointly by Sony and Panasonic. See for example
http://www.avchd-info.org/

Some people seem to erroneously equate AVCHD with the video codec MPEG4 AVC, also known as MPEG4 part 10 or H.264. AVCHD uses the MPEG4 AVC video codec, but the standard encompasses more than the video codec, since it also specifies the audio and subtitle streams, and the container, as I have said before, plus the file directory structure. Not all AVC codec settings are allowed in AVCHD. MP4 may contain HD AVC but that does not make it AVCHD.

>>> "Eagerly awaiting the results of your trials, Peter."

Well, I just performed a test similar to one that I had done some time ago, as follows:

I pointed my Sony AVCHD camera at a rotating record player turntable with a white paper disk on it and a single diameter line. I recorded this for 47 minutes. This produced three files on the camera hard disk with file lengths of 2125234176, 2125037568, and 1955168256 bytes.

I copied them to my computer and concatenated them using the Copy /B command, getting a file of length 6205440000 bytes.

I transferred the shooting session from my camera to my computer using the supplied PMB software, and got a single file of length 6205440000 bytes, and named according to the shooting date and time with a m2ts extension. (The files in the camera have a MTS extension because the file system cannot support 4-letter extensions. The file system also cannot support more than 2GB file sizes, so that is why there were three files for a single shoot.)

I used the FC /B command to compare the PMB transferred file and the concatenated file and there were no differences. Thus PMB concatenates the files.

I used the normal Vegas explorer to assemble the three part files on the timeline, and noted a slight jump at the two junctions. I then added the PMB file to the Vegas timeline under the three part files, and turned the opacity down to 50 % on the latter. The second and third part files did not line up. I found that if I advanced the second and third files to leave a 2-frame gap between the parts, the two videos lined up. The ends of each track also now lined up.

Thus, as is well known, you should not drag the parts of a single AVCHD shoot directly to the timeline, but should either use device explorer, as bastinado has suggested, or first concatenate the parts using your preferred method. I normally use the Copy /B command, but many other software programs will also do the job.

Musicvid, I now eagerly await your trials to indicate where concatenating the part files of a single AVCHD shoot does not work properly.
Kevin R wrote on 11/29/2012, 4:51 AM
As I previously wrote:

>>> How one device splits files does not assure every device behaves similarly.

If you have tested your device, by all means use a successful workflow. Your confidence in your equipment does little to persuade me that all AVCHD equipment splits files identically.

What about the problems joining MP4 files? What do you suppose the difference is? How can you explain this in contrast with AVCHD such that we can all be assured that AVCHD can always be concatenated?
PeterDuke wrote on 11/29/2012, 11:42 PM
I would be confident that all AVCHD Sony cameras behave the same and almost certain that all Panasonic would also, being a cocreator of the AVCHD standard. I can't vouch that all licencees of the standard fully abide by it of course.

If you doubt my findings to be universal, then please provide evidence to the contrary. You only have to find one that doesn't, to prove your point, whereas I would have to test every AVCHD camera model that has ever been made to prove mine.

I have no experience with MP4 cameras. I thought that they might follow the pattern, but apparently not.
Barry W. Hull wrote on 11/30/2012, 8:24 AM
Peter Duke wins!

(sorry, my bit of humor as I read this thread and try to learn something)