Originally Posted by JHBrandt
One problem HomeWorX users are likely to encounter more and more is transferring recordings between 7802 and 7816 boxes. The firmware for the two SoC chips uses a slightly different format, rendering the recordings incompatible.
However, I just tested the trick of changing the file extension from .mts to .ts. This trick is usually employed to restore DD 5.1 to recordings, but it also renders SD 7802 recordings playable on a 7816 box and vice versa.
HD 7802 recordings also played on a 7816 box, but weren't really watchable. The audio and video kept pausing, as if the 7816 couldn't quite decode the 7802 recording in real time. The recording played fine on its native 7802 box, even renamed.
One other curious observation: both recording formats also play on my PC, but the 7802 recording format plays with no audio! I haven't found a fix for this yet, so for now, I'd definitely prefer a 7816 if I planned to play the recording on my PC. Unfortunately, 7816 boxes are getting harder to find. It seems most brands have switched to the 7802 within the past year.
Using a hex editor, I just did a little research into the differences between the 7802 and 7816 recording formats.
Both formats are true .M2TS files, consisting of a series of 192-byte packets, consisting of a 4-byte sequence number followed by the letter G and 187 bytes of data. The difference I saw was that the 7816 format starts with 16 packets (3K) of "metadata" which the 7802 format lacks. For reasons I don't understand, the "metadata" packets all have identical sequence numbers of hex 021E2176. Once you get past the metadata packets, the 7816 files go to sequence number 0 and start incrementing by small amounts (they serve as timestamps).
The 7802 recordings contain no metadata - they just start with a sequence 0 packet and increment from there - but each recording has a companion file with the extension .META. These files contain packets similar to the packets at the start of the 7816 files (same weird hex 021E2176 sequence numbers), but there are 32 of them (6K) instead of just 16. Interestingly, the .META files don't seem to be required for playback.
I haven't tried to delve into the contents of the metadata packets yet.
Evidently, each chip's firmware checks .MTS recordings to see if it has its "own" format, but if you rename it to .TS, it "thinks" it's a "foreign" video and doesn't care.
I don't know if that's the only difference, but if so, it should be easy to convert from 7816 to 7802: just strip off the first 3K of data and copy the rest of the file.
I found a freeware Australian program called Partcopy
that can handle that task. Just copy from byte 3072 to the end.
Not sure about going from 7802 to 7816, though: could you just prepend a 6K .META file to the recording, or would you have to cut it in half and prepend only the first 3K of it? More experiments to come, when I get the time....
Turns out that doesn't work! Neither prepending the whole 6K .META file, nor prepending just the first 3K of it, renders a 7802 recording playable on a 7816 box. Renaming the file extension is the only trick that works, and even that trick doesn't necessarily work with HD recordings. Luckily, moving a recording from a 7802 box to a 7816 box isn't that common.