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21st April 2019, 02:01 | #1 | Link |
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Audio subtly lags behind video - how to fix?
I have an MKV file that has an issue with the audio - it subtly lags behind the video. They start in sync, and then over the course of the whole clip they drift out of sync.
My first idea was that the video framerate is specified wrong by 1, but a quick calculation shows that the effect would be MUCH more pronounced then. I'm at a loss how this could have happened, and better yet - how do I correct it now, since I don't have access to the original source from which it was encoded anymore? Here's the output from MediaInfo: Code:
General Unique ID : [Redacted] Complete name : [Redacted] Format : Matroska Format version : Version 4 File size : 823 MiB Duration : 22 min 17 s Overall bit rate : 5 164 kb/s Encoded date : UTC 2017-10-16 18:54:58 Writing application : mkvmerge v17.0.0 ('Be Ur Friend') 64-bit Writing library : libebml v1.3.5 + libmatroska v1.4.8 Video ID : 1 Format : AVC Format/Info : Advanced Video Codec Format profile : High@L4 Format settings : CABAC / 2 Ref Frames Format settings, CABAC : Yes Format settings, RefFrames : 2 frames Codec ID : V_MPEG4/ISO/AVC Duration : 22 min 14 s Bit rate : 4 920 kb/s Width : 1 920 pixels Height : 1 080 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 24.000 FPS Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Bits/(Pixel*Frame) : 0.099 Stream size : 772 MiB (94%) Writing library : x264 core 115 r1995M 5a37283 Encoding settings : cabac=1 / ref=2 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=4 / sliced_threads=0 / nr=250 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=1 / keyint=250 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=2pass / mbtree=1 / bitrate=4920 / ratetol=1.0 / qcomp=0.60 / qpmin=5 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00 Language : English Default : Yes Forced : No Audio #1 ID : 2 Format : AC-3 Format/Info : Audio Coding 3 Commercial name : Dolby Digital Codec ID : A_AC3 Duration : 22 min 17 s Bit rate mode : Constant Bit rate : 192 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 31.250 FPS (1536 SPF) Bit depth : 16 bits Compression mode : Lossy Stream size : 30.6 MiB (4%) Language : Russian Service kind : Complete Main Default : Yes Forced : No Audio #2 ID : 3 Format : AAC LC SBR Format/Info : Advanced Audio Codec Low Complexity with Spectral Band Replication Commercial name : HE-AAC Format settings : Explicit Codec ID : A_AAC-2 Duration : 22 min 16 s Bit rate : 127 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 23.438 FPS (2048 SPF) Compression mode : Lossy Stream size : 20.2 MiB (2%) Language : English Default : No Forced : No Last edited by Vilx-; 21st April 2019 at 02:03. |
22nd April 2019, 00:56 | #2 | Link |
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You should do a little experimenting with MKVMergeGUI...
Load your MKV, highlight the video stream in the lower left window and have a look at the "Time codes and default duration" section in the right pane. You can either stretch the video by a certain factor, or you can specify the default duration for the video. Optionally you can also adapt the duration in the bitstream to the value in the container. Play around with the options... |
22nd April 2019, 15:30 | #3 | Link |
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Please explain how exactly you created or obtained this file.
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22nd April 2019, 18:15 | #4 | Link | |
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Quote:
And MediaInfo's output (which is only exact down to a second) is not good enough for what you are trying to achieve. MediaInfo can be made to be more precise or you can e.g. use mkvinfo (part of MKVToolNix). Last edited by mkver; 22nd April 2019 at 18:17. |
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22nd April 2019, 20:52 | #5 | Link |
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Video 22min 14sec
Audio 1 22min 17sec Audio 2 22min 16sec Adjust audio in mkvtoolnix gui (right side stretch by) Audio 1 0.9978 Audio 2 0.9985 Or clip the audio accordingly And don't forget to answer LoRd_MuldeR's question Last edited by gonca; 22nd April 2019 at 20:58. |
25th April 2019, 22:58 | #7 | Link | |
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Quote:
One speed/time adjustment can't correct both tracks. Of course if the sync drift is different for the two tracks then 23.976 might work. Either way, won't hurt to try either method Last edited by gonca; 25th April 2019 at 23:01. |
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