M4A标记问题

Question

我在将M4A原子插入文件时遇到了问题。由于原始文件没有udta结构，所以我使用了一个现有的M4A文件作为向导添加了它。

下面是我添加原子时所做的事情：

1. 在内存中构建一个udta原子，
2. 更新moov原子的大小，以便包含到udta原子的大小
3. ，复制文件到第一步原子
4. 的末尾，插入我的udta原子

<代码>H19照例复制其余的。H 210G 211

原始文件和标记文件之间唯一真正的区别是mdat原子被移动了一点，以适应标记。这让我相信在其他原子中有一些关于那个位置的参考，但是我找不到一个。

以下是AtomicParsley的输出：

原始档案：

Atom ftyp @ 0 of size: 36, ends @ 36
Atom moov @ 36 of size: 30156, ends @ 30192
     Atom mvhd @ 44 of size: 108, ends @ 152
     Atom iods @ 152 of size: 33, ends @ 185
     Atom trak @ 185 of size: 30007, ends @ 30192
         Atom tkhd @ 193 of size: 92, ends @ 285
         Atom mdia @ 285 of size: 29907, ends @ 30192
             Atom mdhd @ 293 of size: 32, ends @ 325
             Atom hdlr @ 325 of size: 37, ends @ 362
             Atom minf @ 362 of size: 29830, ends @ 30192
                 Atom smhd @ 370 of size: 16, ends @ 386
                 Atom dinf @ 386 of size: 36, ends @ 422
                     Atom dref @ 394 of size: 28, ends @ 422
                 Atom stbl @ 422 of size: 29770, ends @ 30192
                     Atom stts @ 430 of size: 24, ends @ 454
                     Atom stsd @ 454 of size: 106, ends @ 560
                         Atom mp4a @ 470 of size: 90, ends @ 560
                             Atom esds @ 506 of size: 54, ends @ 560
                     Atom stsz @ 560 of size: 26888, ends @ 27448
                     Atom stsc @ 27448 of size: 40, ends @ 27488
                     Atom stco @ 27488 of size: 2704, ends @ 30192
Atom mdat @ 30192 of size: 2495503, ends @ 2525695

修改文件：

Atom ftyp @ 0 of size: 36, ends @ 36
Atom moov @ 36 of size: 30323, ends @ 30359
     Atom mvhd @ 44 of size: 108, ends @ 152
     Atom iods @ 152 of size: 33, ends @ 185
     Atom trak @ 185 of size: 30007, ends @ 30192
         Atom tkhd @ 193 of size: 92, ends @ 285
         Atom mdia @ 285 of size: 29907, ends @ 30192
             Atom mdhd @ 293 of size: 32, ends @ 325
             Atom hdlr @ 325 of size: 37, ends @ 362
             Atom minf @ 362 of size: 29830, ends @ 30192
                 Atom smhd @ 370 of size: 16, ends @ 386
                 Atom dinf @ 386 of size: 36, ends @ 422
                     Atom dref @ 394 of size: 28, ends @ 422
                 Atom stbl @ 422 of size: 29770, ends @ 30192
                     Atom stts @ 430 of size: 24, ends @ 454
                     Atom stsd @ 454 of size: 106, ends @ 560
                         Atom mp4a @ 470 of size: 90, ends @ 560
                             Atom esds @ 506 of size: 54, ends @ 560
                     Atom stsz @ 560 of size: 26888, ends @ 27448
                     Atom stsc @ 27448 of size: 40, ends @ 27488
                     Atom stco @ 27488 of size: 2704, ends @ 30192
     Atom udta @ 30192 of size: 167, ends @ 30359
         Atom meta @ 30200 of size: 159, ends @ 30359
             Atom ilst @ 30212 of size: 147, ends @ 30359
                 Atom ©ART @ 30220 of size: 35, ends @ 30255
                     Atom data @ 30228 of size: 27, ends @ 30255
                 Atom ©nam @ 30255 of size: 63, ends @ 30318
                     Atom data @ 30263 of size: 55, ends @ 30318
                 Atom ©alb @ 30318 of size: 41, ends @ 30359
                     Atom data @ 30326 of size: 33, ends @ 30359
Atom mdat @ 30359 of size: 2495503, ends @ 2525862

另一个值得注意的是，我作为引用使用的标记文件在udta->meta下有一个hdlr原子，但是添加该标记的副本也没有帮助。如果手动删除udta原子和moov的大小数据，该文件将再次工作。

当我尝试播放标记文件时，我会在各种程序中得到以下错误：

mplayer:
    [aac @ 0x204d720] channel element 0.0 is not allocated
    [aac @ 0x204d720] channel element 0.0 is not allocated
    [aac @ 0x204d720] channel element 3.13 is not allocated
    [aac @ 0x204d720] channel element 2.14 is not allocated
    [aac @ 0x204d720] channel element 2.9 is not allocated
    [aac @ 0x204d720] Prediction is not allowed in AAC-LC.
    [aac @ 0x204d720] channel element 3.1 is not allocated
    [aac @ 0x204d720] channel element 0.3 is not allocated
    ....
totem:
    ** Message: Error: Could not decode stream.
    gstfaad.c(1319): gst_faad_chain (): /GstPlayBin2:play/GstURIDecodeBin:uridecodebin0/GstDecodeBin2:decodebin20/GstFaad:faad0:
    decoding error: Bitstream value not allowed by specification
banshee:
    [Error 08:26:27.610] GStreamer stream error: Decode
    [Error 08:26:27.960] GStreamer stream error: Decode
    [Error 08:26:28.252] GStreamer resource error: NotFound

哦，我多么希望其他99%的程序能识别MP3以外的文件上的ID3标签.

Answer 1

多亏了xdelta3，我找到了标记软件并手动删除的文件与原始文件之间的区别。

问题似乎是'stco‘原子，它是一个使用绝对文件偏移的块列表。对啰!由于我添加了标记，这些偏移现在是无效的。更多代码要做叹息