[mythtv-commits] Ticket #11639: Audio lost after transcode
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noreply at mythtv.org
Thu Jul 4 11:58:17 UTC 2013
#11639: Audio lost after transcode
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Reporter: oli.henning@… | Owner:
Type: Bug Report - General | Status: new
Priority: major | Milestone: unknown
Component: MythTV - Mythtranscode | Version: 0.26-fixes
Severity: medium | Resolution:
Keywords: transcode audio | Ticket locked: 0
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Comment (by oli.henning@…):
Just to help, as far as i can:
I did some further analyzes with the tool {{{tsinfo}}} (from the
{{{tstools}}}-Package):
Problematic recording (audio lost after transcode):
{{{
Packet 1 is PAT
Program list:
Program 1 -> PID 00a4 (164)
Packet 2 is PMT with PID 00a4 (164)
Program 1, version 12, PCR PID 0090 (144)
Program streams:
PID 0090 ( 144) -> Stream type 02 ( 2) H.262/13818-2 video (MPEG-2)
or 11172-2 constrained video
ES info (3 bytes): 52 01 01
Descriptor tag 52 ( 82) (1 byte): 01
PID 0091 ( 145) -> Stream type 03 ( 3) 11172-3 audio (MPEG-1)
ES info (9 bytes): 52 01 02 0a 04 67 65 72 01
Descriptor tag 52 ( 82) (1 byte): 02
Languages: ger/clean effects
PID 0092 ( 146) -> Stream type 03 ( 3) 11172-3 audio (MPEG-1)
ES info (9 bytes): 52 01 03 0a 04 65 6e 67 01
Descriptor tag 52 ( 82) (1 byte): 03
Languages: eng/clean effects
PID 009b ( 155) -> Stream type 81 (129) User private
ES info (12 bytes): 6a 01 00 52 01 05 0a 04 67 65 72 01
DVB AC-3 (1 byte): 00
Descriptor tag 52 ( 82) (1 byte): 05
Languages: ger/clean effects
PID 00ae ( 174) -> Stream type 06 ( 6) H.222.0/13818-1 PES private
data (maybe Dolby/AC-3 in DVB)
ES info (15 bytes): 52 01 04 56 0a 67 65 72 09 00 67 65 72 17 77
Descriptor tag 52 ( 82) (1 byte): 04
Teletext: language=ger, type=Initial, magazine 1, page 0
language=ger, type=Subtitles, magazine 7, page 77
}}}
To compare: A non-problematic recording (of another channel):
{{{
Packet 1 is PAT
Program list:
Program 1 -> PID 02e4 (740)
Packet 2 is PMT with PID 02e4 (740)
Program 1, version 2, PCR PID 02d0 (720)
Program streams:
PID 02d0 ( 720) -> Stream type 02 ( 2) H.262/13818-2 video (MPEG-2)
or 11172-2 constrained video
ES info (3 bytes): 52 01 01
Descriptor tag 52 ( 82) (1 byte): 01
PID 02d1 ( 721) -> Stream type 03 ( 3) 11172-3 audio (MPEG-1)
ES info (9 bytes): 0a 04 64 65 75 01 52 01 03
Languages: deu/clean effects
Descriptor tag 52 ( 82) (1 byte): 03
PID 02db ( 731) -> Stream type 81 (129) User private
ES info (16 bytes): 6a 05 ff 42 08 00 00 0a 04 64 65 75 01 52 01
07
DVB AC-3 (5 bytes): ff 42 08 00 00
Languages: deu/clean effects
Descriptor tag 52 ( 82) (1 byte): 07
PID 02ee ( 750) -> Stream type 06 ( 6) H.222.0/13818-1 PES private
data (maybe Dolby/AC-3 in DVB)
ES info (15 bytes): 52 01 0a 56 0a 64 65 75 09 00 64 65 75 11 49
Descriptor tag 52 ( 82) (1 byte): 0a
Teletext: language=deu, type=Initial, magazine 1, page 0
language=deu, type=Subtitles, magazine 1, page 49
}}}
== Analyze details ==
- Each of the first audio-stream has another value "descriptor tag 52"
- The ordering of the Descriptor-Tags in the "ES info" (of the audio-
stream) is different: In one problematic case, it's tag "0x52" followed by
tag "0x0A". In the non-prblematic-case case it's the other way around.
- The ISO language-codes are different. In one case it's "deu" (for
"deutsch"). In the other case it's "ger" (for "german")
- number of audio-channels are different: the 'problematic' recording hat
3 audio-streams (2*MP2 and 1*AC3) and the non-problematic just hast two
(1*MP2 and 1*AC3)
- The PID-Values differ
== My conclution ==
These differences in the DVB-meta-data (PAT, PMT, PID-Numbers and number
of audio-channels) seems very trivial to me so i think that this is not
the cause of the "audio lost problem"
So the problem is probably within the audio-elementary-streams themselve.
Or it's a specific TS-packet-multiplexing case which could not be handled
by mythtranscode/ffmpeg.
--
Ticket URL: <http://code.mythtv.org/trac/ticket/11639#comment:1>
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