#1614: AAC stream with SBR fails with "channel element 0.1 is not allocated"
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Reporter: iceman12c | Owner: (none)
Type: defect | Status: open
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: AAC SBR | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 0 |
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Comment (by Cosmin Stejerean):
Recently encountered the same issue, on latest ffmpeg 5.0. I took a look
at the attached file to this ticket and it exhibits the same problem as
the streams I'm seeing errors on. This "stereo" audio is actually coded as
single channel elements instead of 1 channel pair element. From the header
we see that it's a typical AAC-LC stereo
{{{
5E291 AudioSpecificConfig (2 bytes)
5E291 audioObjectType - 2 (0x2) - AAC - LC (0 bytes)
5E291 audioObjectType: 2 (0x02) - (5 bits)
5E291 samplingFrequencyIndex: 3 (0x3) - (4 bits) - 48000
(0xBB80)
5E292 channelConfiguration: 2 (0x2) - (4 bits) - Front:
L R
}}}
but the AAC data contains two individual SCEs
{{{
0002C 1 (379 bytes)
0002C raw_data_block (379 bytes)
0002C SCE - single_channel_element (184 bytes)
0002C id_syn_ele: 0 (0x0) - (3 bits) - SCE -
single_channel_element
0002E SCE - single_channel_element (376 bytes)
000E4 id_syn_ele: 0 (0x0) - (3 bits) - SCE -
single_channel_element
00032 END - End (372 bytes)
001A6 id_syn_ele: 7 (0x7) - (3 bits) - END -
End
001A6 byte_alignment: 0 (0x0) - (3 bits)
}}}
whereas a typica AAC stereo channel pair element would look like this
{{{
00913 1 (441 bytes)
00913 raw_data_block (441 bytes)
00913 CPE - channel_pair_element (439 bytes)
00913 id_syn_ele: 1 (0x1) - (3 bits) - CPE -
channel_pair_element
00915 FIL - fill_element (438 bytes)
00ACA id_syn_ele: 6 (0x6) - (3 bits) - FIL -
fill_element
00916 END - End (438 bytes)
00ACB id_syn_ele: 7 (0x7) - (3 bits) - END -
End
}}}
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Ticket URL: <https://trac.ffmpeg.org/ticket/1614#comment:7>
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