Ali Husain
August 16th, 2006, 07:18 AM
just posting this in case it helps anyone else:
i've got a lot of p2 card images made via p2 store, and almost every last MXF file in the VIDEO directory produces a fatal error immediately upon my conversion attempt in BOTH raylight and cineform connect hd. the message is the same: that the format is unknown and that i should check my p2 viewer. now p2 viewer on the same machine opens these p2 card images fine, so...
i copied the "corrupted" p2 card image to a new p2 card image within p2 viewer. and the resulting copied files convert fine in cineform (haven't tried raylight yet).
so to summarize: if you have file "corruption" problems, then you might solve them by copying the p2 directory to a new one with p2 viewer. evidently, the panasonic software is a bit more robust when dealing with funky p2 metadata.
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it seems there are highly inconvenient single points of failure in panasonic's p2 card scheme that make it non-ideal for uncertain field environments and for capture and ingest. if we were dealing with raw dvcproHD or raw DV25 or even raw audio, there is a fairly fine granularity at which corrupted data is resynced. in the simplest example, if you've got raw 16-bit stereo pcm you can lose a byte and at worst you've killed one sample.
if you accept that you're going to be losing bits and piece of your p2 image every now and then, which is an assumption i'd think a reasonable engineer would make, then if you get corruptions in your XML files or in any of the MXF headers, which you should assume you will, you have a problem.
i can see how the XML'icized P2 scheme is nice and elegant for very reliable and safe environments, like your desktop. but this seems like not a very good choice as the center of an abuse-prone yet critical acquisition scheme. if i get just the wrong byte corruption then my entire p2 card can't be read?
now i know there are redundencies in this scheme and you can still pluck data out with the right programs. it looks like panasonic's p2 viewer is the only tool that i have which deals with inconsistencies in the p2 card metadata in a non-tragic way.
if i were writing software to operate on p2 cards, the first thing i would do would be to write a front-end that would check the p2 card metadata against all the headers and lengths for consistancy and build-in a smart repair mechanism, a useful diagnostic output, and i would QA the snot out of it so that it never failed to return some output.
right now i don't think this is happening. i'm seeing common cases failing in alarming ways. for example, there is some p2 card manipulation software (i won't name it) and it dies if you insert an empty p2 card! how hard is that to test? here you go:
if i'm a p2 user i'm going to:
(1) stick in an empty card
(2) stick in a full card
(3) stick in a card with the absolute minimum amount of data
(4) minimum + 1
(5) soemthign in between
(6) max - 1
(7) etc.
if i'm a p2 user i'm going to pull out the card while it's being written (which i saw happen more than once in a single shoot). i'm going to forget to erase it. i'm going to use it to transfer wordprocessor files out in the field somewhere, and then i'm going to forget to erase them and then i'm going to put it back in the camera and try to start shooting.
panasonic and p2 software people: these are all BASIC cases that should be addressed in a graceful way.
dealing with annyoing p2 and mxf issues almost drove me to download the MXF SDK and start to cobble somethign together, until i discovered enough kludgey workarounds for the problems i'm having. anyway i'll stop ranting now. :)
i've got a lot of p2 card images made via p2 store, and almost every last MXF file in the VIDEO directory produces a fatal error immediately upon my conversion attempt in BOTH raylight and cineform connect hd. the message is the same: that the format is unknown and that i should check my p2 viewer. now p2 viewer on the same machine opens these p2 card images fine, so...
i copied the "corrupted" p2 card image to a new p2 card image within p2 viewer. and the resulting copied files convert fine in cineform (haven't tried raylight yet).
so to summarize: if you have file "corruption" problems, then you might solve them by copying the p2 directory to a new one with p2 viewer. evidently, the panasonic software is a bit more robust when dealing with funky p2 metadata.
-----------
it seems there are highly inconvenient single points of failure in panasonic's p2 card scheme that make it non-ideal for uncertain field environments and for capture and ingest. if we were dealing with raw dvcproHD or raw DV25 or even raw audio, there is a fairly fine granularity at which corrupted data is resynced. in the simplest example, if you've got raw 16-bit stereo pcm you can lose a byte and at worst you've killed one sample.
if you accept that you're going to be losing bits and piece of your p2 image every now and then, which is an assumption i'd think a reasonable engineer would make, then if you get corruptions in your XML files or in any of the MXF headers, which you should assume you will, you have a problem.
i can see how the XML'icized P2 scheme is nice and elegant for very reliable and safe environments, like your desktop. but this seems like not a very good choice as the center of an abuse-prone yet critical acquisition scheme. if i get just the wrong byte corruption then my entire p2 card can't be read?
now i know there are redundencies in this scheme and you can still pluck data out with the right programs. it looks like panasonic's p2 viewer is the only tool that i have which deals with inconsistencies in the p2 card metadata in a non-tragic way.
if i were writing software to operate on p2 cards, the first thing i would do would be to write a front-end that would check the p2 card metadata against all the headers and lengths for consistancy and build-in a smart repair mechanism, a useful diagnostic output, and i would QA the snot out of it so that it never failed to return some output.
right now i don't think this is happening. i'm seeing common cases failing in alarming ways. for example, there is some p2 card manipulation software (i won't name it) and it dies if you insert an empty p2 card! how hard is that to test? here you go:
if i'm a p2 user i'm going to:
(1) stick in an empty card
(2) stick in a full card
(3) stick in a card with the absolute minimum amount of data
(4) minimum + 1
(5) soemthign in between
(6) max - 1
(7) etc.
if i'm a p2 user i'm going to pull out the card while it's being written (which i saw happen more than once in a single shoot). i'm going to forget to erase it. i'm going to use it to transfer wordprocessor files out in the field somewhere, and then i'm going to forget to erase them and then i'm going to put it back in the camera and try to start shooting.
panasonic and p2 software people: these are all BASIC cases that should be addressed in a graceful way.
dealing with annyoing p2 and mxf issues almost drove me to download the MXF SDK and start to cobble somethign together, until i discovered enough kludgey workarounds for the problems i'm having. anyway i'll stop ranting now. :)