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<blockquote data-quote="Simon Eves" data-source="post: 214583" data-attributes="member: 4463">With respect to Ben, a 44.1/48 sample rate difference is going to be VERY obvious, as that&#039;s nearly a 10% difference which is a couple of semitones of tuning and it would drift very quickly and obviously. Consumer gear just sometimes doesn&#039;t have very accurate clocking, and two devices can just drift.My fix for this has always been to sync the audio and video at one end, measure the drift at the other end, and compute the speed-up (or slow-down factor) to process the audio (most easily using the Change Speed operation in Audacity) to match. For example, if the recording is two minutes long, and the sound is 0.5s ahead of the video by the end, then it needs to be slowed down by 119.5/120 or 99.5833%. Conversely, if it&#039;s 0.5s behind, it needs to be sped up by 120.5/120 or 100.4166%.The other possible reason is that the 30fps may actually be 29.97fps (US NTSC TV frame rate) and one device or the other, or perhaps your editing software, may be compensating for this and causing a 0.1% drift.</blockquote>

[QUOTE="Simon Eves, post: 214583, member: 4463"] With respect to Ben, a 44.1/48 sample rate difference is going to be VERY obvious, as that's nearly a 10% difference which is a couple of semitones of tuning and it would drift very quickly and obviously. Consumer gear just sometimes doesn't have very accurate clocking, and two devices can just drift. My fix for this has always been to sync the audio and video at one end, measure the drift at the other end, and compute the speed-up (or slow-down factor) to process the audio (most easily using the Change Speed operation in Audacity) to match. For example, if the recording is two minutes long, and the sound is 0.5s ahead of the video by the end, then it needs to be slowed down by 119.5/120 or 99.5833%. Conversely, if it's 0.5s behind, it needs to be sped up by 120.5/120 or 100.4166%. The other possible reason is that the 30fps may actually be 29.97fps (US NTSC TV frame rate) and one device or the other, or perhaps your editing software, may be compensating for this and causing a 0.1% drift. [/QUOTE]

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