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BDMV and the physical layout of discs


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I know I’m treading into territory that has been brought up on this forum by various requesters multiple times in the past. But I still want to bring it up, if anything for an insight into the current and future of burning media on disc (I may have limited knowledge). Lightning UK has said that the BD-R and/or UDF 2.50 standard specifies that there is no logical layer break. While this might be true for data discs, BDMV puts a lot of effort into seamless streaming, PTS layer breaks are those that happen within one stream at a chapter for instance or an arbitrary presentation time.

I have tried to find information on what an image such as ISO consists of, if the UDF filesystem is intricate enough to say which order files should be in, their start and end sectors, or if burning an image results in a file structure of alphabetical order. This has the risk that on DL and TL discs index.bdmv, the first file supposed to be accessed, is on L1 or L2.

Is all this really up to the hardware? Can a virtual UDF filesystem be more specific? Can I manually edit a UDF filesystem, to change the blocks and sectors? I only found the single tool, udftools, on Github and it’s for creating new filesystems.

Here is an example of a CMF FAI file. It’s an XML that very concretely outlines the BDMV disc layout, with start sectors and file sizes. If only I could find a way to make use of this when creating an image or burning to disc.

<?xml version="1.0" encoding="UTF-8"?>
<CMFFilesInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="FAIschema.xsd">
    <FileAddress Path="/BDMV/index.bdmv" Size="264" Access="EXTENT">
      <Extent Start="4320" Size="264" />
    <FileAddress Path="/BDMV/MovieObject.bdmv" Size="470" Access="EXTENT">
      <Extent Start="4321" Size="470" />
    <FileAddress Path="/BDMV/PLAYLIST/00001.mpls" Size="790" Access="EXTENT">
      <Extent Start="4323" Size="790" />
    <FileAddress Path="/BDMV/CLIPINF/00001.clpi" Size="11640" Access="EXTENT">
      <Extent Start="4344" Size="11640" />
    <FileAddress Path="/BDMV/STREAM/00001.m2ts" Size="10275858432" Access="EXTENT">
      <Extent Start="275232" Size="1073676288" />
      <Extent Start="799488" Size="1073676288" />
      <Extent Start="1323744" Size="1073676288" />
      <Extent Start="1848000" Size="1073676288" />
      <Extent Start="2372256" Size="1073676288" />
      <Extent Start="2896512" Size="1073676288" />
      <Extent Start="3420768" Size="1073676288" />
      <Extent Start="3945024" Size="1073676288" />
      <Extent Start="4469280" Size="1073676288" />
      <Extent Start="4993536" Size="612771840" />
    <FileAddress Path="/BDMV/BACKUP/PLAYLIST/00001.mpls" Size="214" Access="EXTENT">
      <Extent Start="16127906" Size="214" />


After searching a week for any solution to layout my disc when burning, I gave up and fed Imgburn the image in hope for the best. As expected, no layer breaks were honored and what’s worse, break L0 had bad sectors and the video is corrupted for 12 frames or so. L1 break was fine though. The only hack I can think of, besides if the possibility to edit the UDF FS exists, is to insert useless blank clips around the layer breaks. And if PTS breaks are needed, chop the stream into several parts while inserting these fillers.

I appreciate if anyone has an opinion on this problem, and I hope that someone agrees that it’s not an issue without merit.

Edited by psisys
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