Audio Gradually Drifts Out of Sync in Converted DV files

[mirbramo94]

i see many posts here describing what i am experiencing, and many posts on how to edit a video to reduce the audio drift problem, but i have found no solution on how to FIX it. I have many dv files from copying over tapes from my old 8mm camera. These dv files play perfectly, no audio video sync problems whatsoever. However, when i try to convert then to ANY format, using ANY video conversion softwares (and i have tried MANY), the resulting video gradually drifts out of sync with the audio. The video starts off fine, but by the end, the audio and video are out of sync by a few seconds! This puzzles me because the original dv plays perfectly! How can i convert these dv files without that happening? i don't want to have to deal with the messed up output file, and manually try to match up the audio and video where they are not in sync, as this would take forever (i have A LOT of videos i need to convert). I need a solution that will prevent it to begin with. How do i convert these dv files without the resulting file gradually drifting out of sync with the video? I have spent countless hours trying to resolve this and it is driving me insane. Please help, if you can!

[Guest34343]

Does it happen with only a single file or only when you join a lot of them?

For a single file there's really no reason it should happen, so can you tell us the exact process you used that causes this issue? I know you said you tried many, but let's hear specifics about one of them and go from there.

[hech54]

using ANY video conversion softwares

Yes but are they ANY good?

[yoda313]

Instead of using any software use the good ones:

format factory for file to file conversion
avstodvd for dvd creation
ripbot 264 for file to file conversion
handbrake for file to file conversion

I believe you can get a video_ts folder out of format factory however I've only used it for file to file conversion.

These four programs are all freeware and are among the most frequently recommended pieces of software to use here on videohelp.

Of course there are others but these are close to a "gold standard" for repeatable quality output.

Other notables - bdrebuilder, super, xvid4psp, avchdcoder,

Again it depends on what you need from your file.

One other thing to always consider is to recapture your dv material. Perhaps there were errors during capture?

[mirbramo94]

The dv files are single files, not joined together. I know it is not a dv capture issue because i have tried to recapture multiple times with multiple different software, and the dv files play perfectly. The problem arises when i convert them to another format. I have tried using handbrake to convert to mpeg4, i have tried using quicktime to convert to many different formats, i have tried ffmeg, mpegstreamclip, i even tried on a different computer that runs a different operating system. the resulting files all have the same exact problem. They start out video-audio synced, and gradually it slips out of sync, and by the end of the video, it is several seconds off. the original dv file does NOT have this problem whatsoever. Thanks to everyone who is trying to help. I really really appreciate it. I really need this resolved!

[manono]

You're maybe changing the framerate? You say the sources are in synch but go off-synch by several seconds after being converted. What is the typical length of the source files?

To find out if it's the audio or video going off, compare the source audio and video length with the output audio and video length.

I also have done many DV captures (but from VHS tapes) with never the problem you describe after conversion to DVD. Have you tried WinDV, by chance, to do the capturing? And you never drop any frames?

[mirbramo94]

i'm not changing the framerate, i always choose the option to use the source one. the source files are usually over an hour, like an hour and 10 minutes? one of the videos has a source length of 1:04:35.30 and the output is video 1:04:35.30 and audio 1:04:35.81. i don't know where i'm going wrong.

[manono]

Ah, so it's the audio going off? But that's only half a second difference. Maybe it's a combination of a delay with a progressive out-of-synch. I assume the audio is initially PCM WAV audio. It should be a simple matter to demux it (and check the length) and then convert it to the final desired audio format separately and see if the length remains the same as the source, or also lengthens.

Are you changing the audio samplerate during this process (capping at 44,100 and changing to 48,000, for example)?

I don't guess you have any TBCs in the capture chain?

[mirbramo94]

I don't think i understood any of that lol. what are TBCs?

[manono]

TBCs:

http://www.digitalfaq.com/forum/video-restore/2251-tbc-time-base.html

I've seen an audio's length change during samplerate changes when using certain software (BeSweet, for example). If you extract your audio from the source and compare it with the final audio in something like MediaInfo, it should tell you. It'll say either 44.1KHz or 48.0KHz. If possible, you want to cap in the same samplerate as you intend to end up with (48.0KHz, if for DVD).

Edited to change 'framerate' to 'samplerate'

[mirbramo94]

I'm don't know a lot of technical stuff about videos

here's the source info from mediainfo:

General
Complete name : /Volumes/500GB/Tapes/Tape 14.dv
Format : DV
Commercial name : DVCPRO
File size : 18.9 GiB
Duration : 1h 33mn
Overall bit rate mode : Constant
Overall bit rate : 28.8 Mbps

Video
Format : DV
Commercial name : DVCPRO
Duration : 1h 33mn
Bit rate mode : Constant
Bit rate : 24.4 Mbps
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 29.970 fps
Standard : NTSC
Chroma subsampling : 4:1:1
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Bottom Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 2.357
Stream size : 16.0 GiB (85%)

Audio
ID : 0
Format : PCM
Duration : 1h 33mn
Bit rate mode : Constant
Bit rate : 1 536 Kbps
Encoded bit rate : 0 bps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 1.01 GiB (5%)

Does that provide any info you need?

[mirbramo94]

and this is the output:

General

Complete name : /Volumes/500GB/Tape /Tape 14.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 1.69 GiB
Duration : 1h 33mn
Overall bit rate mode : Variable
Overall bit rate : 2 577 Kbps
Encoded date : UTC 2012-08-30 17:09:55
Tagged date : UTC 2012-08-30 18:22:44
Writing application : HandBrake 0.9.8 2012071800

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L3.0
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1h 33mn
Bit rate mode : Variable
Bit rate : 2 395 Kbps
Width : 716 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 29.970 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.233
Stream size : 1.57 GiB (93%)
Writing library : x264 core 120
Encoding settings : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=3 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=300 / keyint_min=30 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.60 / qpmin=3 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Encoded date : UTC 2012-08-30 17:09:55
Tagged date : UTC 2012-08-30 18:22:44
Color primaries : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M
Transfer characteristics : BT.709-5, BT.1361
Matrix coefficients : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 1h 33mn
Bit rate mode : Variable
Bit rate : 178 Kbps
Maximum bit rate : 191 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 120 MiB (7%)
Encoded date : UTC 2012-08-30 17:09:55
Tagged date : UTC 2012-08-30 18:22:44

[poisondeathray]

what are your mac hardware specs ? It might be a playback problem

what software player are you using ? Try mplayer osx extended, or vlc

The A/V durations match in the mediainfo report for the encoded file

[mirbramo94]

i do use vlc. i don't think it's a playback problem because i also tried the conversion and the playback on my netbook which runs ubuntu. the result was exactly the same. also the problem remains when i try to burn the converted file to a dvd, and play it on my dvd player.

my mac specs are
Hardware Overview:

Model Name: MacBook Pro
Model Identifier: MacBookPro7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 8 GB
Bus Speed: 1.07 GHz
Boot ROM Version: MBP71.0039.B0B
SMC Version (system): 1.62f6
Serial Number (system): W8036N4YATM
Hardware UUID: 252AE12E-CABD-5FE6-8754-2B3E230BC637
Sudden Motion Sensor:
State: Enabled

[mirbramo94]

i don't know if this changes anything, but i am using an analog to digital converter to transfer the 8mm tapes from my old nikon camera.

[poisondeathray]

i don't know if this changes anything, but i am using an analog to digital converter to transfer the 8mm tapes from my old nikon camera.

It shouldn't make a difference. If the DV files play in sync, everything should be ok. The mediainfo reports all say the same duration for audio & video . A progressive/gradual out of sync problem usually means audio & video lengths don't match . It doesn' t make any sense

[poisondeathray]

Sometimes mediainfo may misreport or can be wrong

Can you open up the original audio and encoded audio in an audio editor & compare lengths? e.g. audacity

for mac
http://audacity.sourceforge.net/download/mac

[manono]

Thanks, pdr, for stepping in. With the samplerates being the same before and after, and with me knowing nothing about Macs, I'm stumped. Plus, MediaInfo isn't precise enough with the lengths since we're talking about the audio being only a few seconds off in the output file. Knowing their exact lengths will help. Also, is AAC audio commonly encoded as VBR? I have no idea myself.

[poisondeathray]

Plus, MediaInfo isn't precise enough with the lengths since we're talking about the audio being only a few seconds off in the output file.

That's true, but it should report to ms accuracy. If it's even seconds, that means it's right on the button 000ms (at least it's that way with PC version of mediainfo)

mirbramo94 - while you're at it , use the advanced mode for mediainfo (debug=>advanced mode) , and it should report the framecount as well . Eitherway, mediainfo isn't entirely reliable for these things, but it should give you more information

Also, is AAC audio commonly encoded as VBR?

yes

[mirbramo94]

original 1:33:55.334
encoded 1:33:55.349

[poisondeathray]

were those values from audacity ?

AAC encoders actually add delay padding at the beginning (if you zoom into the waveform you should see it), so it still doesn't explain your observed results . Besides, you said it was "a few seconds" off, not a few ms off

Can you try another player anyways, like mplayer osx extended ? some VLC versions are known to be buggy

[mirbramo94]

just tried it. same exact problem.

[mirbramo94]

and yes those values were from audacity

[manono]

just tried it. same exact problem.

It starts off in synch and then slowly drifts off? This is very unusual.

[2Bdecided]

i don't know if this changes anything, but i am using an analog to digital converter to transfer the 8mm tapes from my old nikon camera.

Which converter?


I don't think there's any specific A/V sync information in DV files, is there? It just relies on a specific number of audio samples per video frame (or several frames, to handle the awkward NTSC fraction). Even unlocked DV audio stays within 1/3rd of a frame accurate and (in a single file) won't accumulate more sync error.

If the DV decoder did something strange, it could account for it - but I'm guessing a Mac knows how to decode DV If you're seeing exactly the same sync errors whatever software you use and format you transcode to, it does point to the original files or the DV decoder used when transcoding.

It could be that the DV files aren't strictly to spec (e.g. slightly wrong number of audio samples per video frame), but that with the audio packed with the video they play OK (because the audio and video information is physically adjacent in the file, and your player is generous!), while with the audio separated from the video or decoded in a different way the error is revealed.

When you say the DV files are in-sync, is this known simply by skipping to the end and checking (which causes the decoder to resync when you skip), or because you've played the file from beginning to end without interruption (which is effectively what the decoder will do when you transcode the file for DVD etc)?

I'm just throwing ideas out there - others will probably know better - but given that it's a bit of an enigma I though I'd have a guess!

Cheers,
David.

[Cornucopia]

Sounds to me like encoded file is REPORTING 29.970 fps but playing 30fps. But audio is still running constant 48kHz (or some alternate variation on this).

What FPS setting are you giving the encoder? "Same as source"? 29.97? 30? or (best) "30000/1001"?

Scott

[lordsmurf]

Can you try another player anyways, like mplayer osx extended ?
some VLC versions are known to be buggy

I was going to suggest this, too.
On Mac, VLC is really a big piece of crap as a player.

The Mac needs to be entirely removed from playback testing. Play the file on a Windows computer.

[mirbramo94]

it's not the mac or the player. i have tried the same conversion and playback on both a windows computer and linux. and i have tried multiple converters and players on each. this is getting so frustrating. Cornucopia, i do same as source.