[FFmpeg-user] ffmpeg with damaged dv from tape capture

[Dave Rice]

On Mar 8, 2013, at 8:24 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Dave Rice <dave <at> dericed.com> writes:
> 
>>> But didn't you originally report another issue?
>>> One where no audio was detected in a raw dv stream?
>> 
>> Yes. In that case my initial frame contained audio DIF 
>> blocks with error codes and ffmpeg interpreted the
>> whole stream as only a video track with no audio.
> 
> Could you provide a slightly longer sample?

I produced a sample by using my earlier submitted error.dv and cutting off the first 774 frames. But I've seen the same in many dvgrab captures since the first frame from a tape read is occasionally in similar condition.
To make the sample I used: tail -c +92880001 error.dv > error_no_audio_detected.dv
92880001 = 120,000 bytes/frame (NTSC dv25) * 774 frames (since I know the 775th contains audio error codes) + 1 byte start on the 775th frame.
The result is uploaded here: http://dericed.com/samples/error_no_audio_detected.dv

Here is ffmpeg -i

ffmpeg -i error_no_audio_detected.dv 
ffmpeg version 1.1.git Copyright (c) 2000-2013 the FFmpeg developers
  built on Feb 26 2013 21:44:50 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-ffplay --enable-libopenjpeg --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1/include/openjpeg-1.5 '
  libavutil      52. 17.103 / 52. 17.103
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.100 / 54. 63.100
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 41.100 /  3. 41.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[dv @ 0x7f92a300f200] Detected timecode is invalid
[dvvideo @ 0x7f92a300f800] AC EOB marker is absent pos=65

[ ... many similar lines removed ... ]

[dvvideo @ 0x7f92a300f800] AC EOB marker is absent pos=65
[dv @ 0x7f92a300f200] Estimating duration from bitrate, this may be inaccurate
Input #0, dv, from 'error_no_audio_detected.dv':
  Duration: 00:00:34.20, start: 0.000000, bitrate: 28771 kb/s
    Stream #0:0: Video: dvvideo, yuv411p, 720x480, 28771 kb/s, SAR 8:9 DAR 4:3, 29.97 tbr, 29.97 tbn, 29.97 tbc
At least one output file must be specified


FFmpeg detects only video. During this frame the playback deck had a head clog so half of the video is produced via video error concealment and copied from the prior frame and half of the audio is filled with the error code.

Here I use head to pipe the first frame (120000 bytes) to xxd to make 80 bytes lines (80 bytes is one DV dif block) and then grep out the audio DIF blocks (which all start with 0x7). You can see that half the audio data is the error code 0x8000. This frame should play a full frame of audio but should naturally be choppy because of the lost data from the tape read.

head -c 120000 error_no_audio_detected.dv | xxd -c 80 -ps | grep ^7
7f0700ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0701ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0702ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0703ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0704ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0705ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0706ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0707ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f0708ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
711700505600c0c002b1008efe23001bfdb9036f02ab00befcc3fec6ffba0008017afe3c0238fe9f0110ff0afd550321037a0111fddefe20fe6b01fc00c70037ff7f0062ff80fdf5fdf4ff1b049902a0
7117015133cfa0ffff17ffa7fdaffdb3ffb5048f01f4fe0efd8ffd890154024d008100dc036aff14fda6fe0dfed4037101cc020dfca3fcccff5300b10128fe13021f00240081febcfcfe02ab031201c2
711702fffffffffffe6d004effcafca002f003820174fcc5ff72febf00be0047004600d2fe940046fe6bfd4fffb90486029fff42fd9efbfe010802850081001d033dff40fe6cfd84fe3902e70256ffff
711703ffffffffff000201a8fee9fde2fee803cd0231fe18fd4bfd2700a0004500a4ff66037dfeff00930030fd8203ad030c019efcaffba8ff3001ff014efe0d0188ffbdfff2fe65fd9501410457016e
711704ffffffffffff14ff8efe0ffe90033503880154fce9ff15fda9022802e4003fffde0047012afd7bfdacff4d0469027fff0cfd11fb1600c1010dfff000c00336ff88008cfd89fdf6032d015e0000
711705ffffffffffff51ff91ffb7fd6c03500320006efaf1fd20ffc3013b0171fe870131ff57ff61fe24fe0f021504410128ff71feeffd03022e00db002affebffc100e2fdc0fdbefee9047602600000
711706ffffffffff02240032fc67fe75ff97038a0243ff7ffc55fc53ffcd010900b8ffe602b2fef5ffcbff6bfd1003b903d40249fcfcfd18fed100cf0034fdfd00f2006cfff5ff56fe8a002a03e101cf
711707fffffffffffdb4000bfd95fdf0008203c40197fdb2feaefd5401eb0183001a005e022a0092fd2efd32ff21042a020a0109fd06fd3dfe53023700eefee202dfff4f00b3ff3bfd3603d202aa01f2
711708fffffffffffdad009fff7ffe6703f104e900a1fbd0fe07004c01570139fe820126ff26ff9efe0cfebc003003d3023efe61fec6fc3a01eb02a1ff79011901bb000afd6ffbcdfe66041102cbffff
7f2700ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2701ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2702ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2703ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2704ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2705ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2706ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2707ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f2708ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
713700505600c0c002040047fcb6febaff6c037d02a6ff44fc65fc650022009100c3001e0293fedd0063ff59fd5303a3042001bafcfcfd2cfe980101004cfe0800e9ffd40006ff17fe50005a040201ea
7137015133cfa0fffe12fff4fe31fe780104043a014bfccbff24fdce01e401e8ffffffe401c600b7fd1dfd78feb6043402670086fd3cfd3cfe58024100b7ff79034effa000affe95fd480414028a01ad
713702fffffffffffd200008ff91fe2403cc045c0029fb66fd9e008301de016efdf2019dffb5ffd4fe1fff1e009703b6020dfe5afeb2fc2201f20266ffb000fa01000011fd04fc12fe5c04b902980000
713703ffffffffff01f900acfd3bff30fe64036d02050100fceafe3fffff00c80161fe2001e1ff0600e7fedcfd9003d8036a01acfd4efe40fece0196004fffa2001c00c6ff7bfe59fe24ff3c0495024f
713704fffffffffffdfaffaafce3fdf6001003a30283fe58fd33fd0e016201fc0061015003a0fee7fdb8fdeaff3702df01b701f4fcdefcd9ff440105013dfdfb0222ffe6007bfecffd46028102e501e5
713705fffffffffffeb40018ffa8fdc902eb040101e5fca2ff8bfef50064004e000400c3fe420062fe87fd2cff6a044102bfff24fdc8fcb50109029b0071006002d7ff8bfe4bfd75fe5902f60291ffff
713706ffffffffff007f0204feecfd99ff0a044501c4fda0fe0dfd1600c9012b009affb5033aff4c0061ffd4fd5203e8027c017cfcadfb93ff5001850170fe0801680011fff4fe82fd210165044d0128
713707fffffffffffeec0028fe3dfdbb036703bb0120fd10ff38fde001f102ef0087ffe9003200d4fe40fd6efeff0431028bff49fd23fb1700d80143000300ba034dff23002ffd71fe0c02de01250000
713708ffffffffff0048ffc30081fccd03b4036500effad9fd9eff87010300eefe570194fed2ff9bfe04fd79021e03ea00adffc3feb9fd7f025a013d0060ff69ffd400bcfdb2fdf0ff26040f02caf513
7f4700ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4701ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4702ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4703ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4704ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4705ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4706ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4707ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f4708ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
715700505601c0c00345006dff6b000efcd3037b039c00d1fb18fe0cffab005c00b7fe5801c3fea2ffd8fe48fc60027f04c60063ff1bfe81fdd502ba018b0050feb4003a010cfd8bfdd8ff57044e036f
7157015133cfa0ffff4c0132fee2fd48fec10454016afdf8fdb0fcdf019401430040ffab0331ff27ff87fea5fe1904af01d401e0fc98fb40ffa2016401f9fdc001e300aa002efe4dfce401f7045000ff
715702fffffffffffe200007fe6bfccf03e3037300f9fceefed6fde7021602c900aeffabffa30091fe93fcbaff3e04f402b6ff5afcfbfb29010201e5003b00bb03b2ff52fffcfd69fdd902a0017cfffe
715703ffffffffff01e20082fcf5fe60ff53049902a0fefdfc20fc12fff6008200c4ffb602daff13003eff5efcc203a004250180fcd1fc9bfe9401760078fdf0011aff94ffd3feeffe1a00c6044f021e
715704ffffffffffff04fff5fdb0fe3f01e004910160fc91ff97fdbf022e01f2ffd0000100c60146fca6fd35fe4b051f0300ff3bfd2efc37fe99020f0093ff7003b6ff91007efdd1fd280434025a01a4
715705fffffffffffd83ffabffbbfd9f03d70487007bfa98fda000b901bd01c0fdd8015bffcaffbbfe06ff2601450456020ffe8cfeadfbe902430286ffda012300c30034fc81fbeffe9c05510295fffe
715706ffffffffff02830039fc59fe9dff14038501ee00bcfc8bfe0eff9b00f2011afe1e0207fe4e00d0fed3fda2046903ef02a2fcb0fd73feaa016a0020ff0d00b500ceff67fea9fe0fff2604f20213
715707fffffffffffd49ffe9fce5fe16ffae03f702b3fe1dfd0efd2c016f01a900830192033bff50fd91fd35ff36036a01a701b9fc84fcf9feee01790142fe2b023eff9c00a7ff08fcf8034702c0025d
715708fffffffffffdbd0175ff32fd9e0388046001b1fc19feacff350075011fff9500ddfec00035fdc9fd8bff730419030ffed7fe27fc2e013002a80087009b024fffadfdd7fc51fe2b03ed030effff
7f6700ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6701ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6702ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6703ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6704ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6705ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6706ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6707ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f6708ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
717700505601c0c0032affeffc1efe81ffd203e5020afffefcebfd4fff7d00b90149feae0214fe1200bbfeccfd43046c03f6023bfd07fd34febe014afff9feca00d100b6ff4dfe90fdd6ff7304fa0216
7177015133cfa0fffd7cff9ffd4efde3ffcc04f901e4fdf7fdd4fd4d015501d10023016a0308003afd18fd8bfee5040801fd013efc89fd62fe5d02190118fe8102b0ff4d00c2ff1dfc24040d02ae0254
717702fffffffffffd9d0189ffc8fd60043604a4010afb7afea3ff5f00de00c4ff460168fec00074fd64fe52ff8104170289fe9efe29fba2016e02bc005f00ad01bcffe1fd38fbc4fe45047c02f7fffe
717703ffffffffff031fffebfefe0025fc8e03a7027500dafba0fdecffcd006300e3fe7e020ffeae0048fe27fc5e02d5049a0045fe1efea3fdea01fc0159008bfe9fffe20106fd8afe20feef047a02b4
717704fffffffffffe8e00c9fe7ffd7cff3003dd018bfdc8fd84fc8d01a801e9006b000f038dfe60ff30feedfe1a03bd01cf0279fc7dfba9ff9100f601f6fd97024400d7001ffe17fd350214042c00e4
717705fffffffffffdd4ff59fe79fc98037403860146fcd6fecefde701700207008dffeeff5500bdfe7cfc9fffb905120273ff48fcc3fb56015e0242005b00b403cfff39ff7ffdddfdbf02fd0217fffe
717706ffffffffff0196012dfd0efdfaff01045802ccfe96fc80fbeb008c009e00a0003c0368ff2c007afffafc2f036b03ab0188fcd6fc56fe8c01dc00e0fdf2010cff710023fec1fe16010f047201d3
717707ffffffffffff2c0035fd79feca029904640117fc6dff92fd7b028d02960017ffcb00c7011ffc91fd3bfe1a0530031aff8ffd38fbeeff4e01bb0085ffcc0373ffb300b2fd9ffdca03e2023401ea
717708fffffffffffea2ff63ffa4fde604190441010bfa2afd0f005801e6018efdce0102ff53fea6fe08fe9001ab0481019aff24fec9fca902c90244ffd900f2010500a5fcd1fc97feb704b202a1ffff
7f8700ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8701ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8702ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8703ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8704ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8705ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8706ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8707ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
7f8708ffffffffff800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000800080008000
719700505601c0c000420191fe0efdd3feab03e102cdfe77fcbafcc600f9fff00080ffd70386ff1900a4ffc5fd1b03f20367018ffcc5fbc0feeb02290151fdea0164ff7b0056fe62fdc3014804af01bc
7197015133cfa0fffe83ffd6fdf6ff2a033e03f5011bfc2eff26fdab02a7034e002bff7e00ec00defccffd6cfe9004a9031aff92fd20fb9100210167003e006e0349000300fffd4ffdeb038b020e0000
719702fffffffffffecefee4ff29fe6903a403c10090fa4cfcf3ffed01bd0170fdfe0119ff7afe7efe72fe2901e404a60183ff3efe80fd0902d80173ffcd007600830111fd6ffd32fec704bd02b0fffe
719703ffffffffff02850027fc1ffe460000048c01caffc2fc95fc80ff59011d010efeee025ffee6ffbafebefcfd046203b30223fd20fcd9ff2300e30007fe45011200d1ff87fef5fe1dffea0489021a
719704fffffffffffd87ffdbfd24fd5d0068048901dbfe00fe82fd2c01a001a7ffd2012202a7009bfcfcfd54fed40427025600c6fcbcfd09fe1e0244010efe3b02eaff1500b0ff1ffc2703e802e80222
719705fffffffffffddb0095fff0fe35042b057f00fafb60ff0dfff600dc00b7ff10013cfec8003bfdf0fe83ff97041c027dfe62fe1ffbd001cf02ffffbd011901d40005fd37fb72fe89046c0302ffff
719706ffffffffff03030019fe8700bdfcd10411025c00f2fbcafea2ff5b0048010ffe0c0295fe6700a0fe82fd1102ea03d100c0fddefdd6fe1101d1014700a5ff1dffc3002efdb0fe0bfeb404b6027a
719707ffffffffffff3f00cbfe40fd7aff7c04a001f2fd50fdcffd550160028900bb009c035bfe95fe8cfe6ffde8036802020252fc4cfc32ff5c00690176fdaf022900830054fe55fcf3026c03db0173
719708fffffffffffd84000eff08fc3c02ff03d10167fc98ff21fe7d00df0162006d006fff830050fe5efcfdffb1048802c6ff46fd09fb4801520279007e005e03a6fef9feddfd64fde803640288ffff

I notice that ffmpeg also reports: [dv @ 0x7f92a300f200] Detected timecode is invalid
I output the subcode DIF blocks of the first frame:

head -c 120000 error_no_audio_detected.dv | xxd -c 80 -ps | grep ^3
3f0700ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f0701ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f17008720ff1305141001f3a1ff1400000000f302ff1305141001f723ff1305141001f3a4ff1400000000f305ff1305141001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f17018726ff1305141001f3a7ff1400000000f308ff1305141001f729ff1305141001f3aaff1400000000830bff1305141001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f2700ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f2701ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f37008780ff1305141001f3a1ff1400000000f302ff1305141001f783ff1305141001f3a4ff1400000000f305ff1305141001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f37018786ff1305141001f3a7ff1400000000f308ff1305141001f789ff1305141001f3aaff1400000000830bff1305141001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f4700ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f4701ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f570007e0ff130514100173a1ffffffffffff7302ffffffffffff77e3ff130514100173a4ffffffffffff7305ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f570107e6ff130514100173a7ffffffffffff7308ffffffffffff77e9ff130514100173aaffffffffffff030bffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f6700ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f6701ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f77000840ff130514100173a1ffffffffffff7302ffffffffffff7843ff130514100173a4ffffffffffff7305ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f77010846ff130514100173a7ffffffffffff7308ffffffffffff7849ff130514100173aaffffffffffff030bffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f8700ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f8701ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f970008a0ff130514100173a1ffffffffffff7302ffffffffffff78a3ff130514100173a4ffffffffffff7305ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
3f970108a6ff130514100173a7ffffffffffff7308ffffffffffff78a9ff130514100173aaffffffffffff030bffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff

Because of the head clog during playback of this first frame, the first set of DV subcode DIF blocks are simply filled with 0xffff, but the subcode data read by the other head (for example the third and fourth subcode dif blocks of the frame) are fine. In those lines the DV timecode translates to 01:10:14:05. I suspect that ffmpeg is only using the first DIF sequence to determine audio channel configuration and timecode and not probing to subsequent dif sequences.

Dave Rice