Replacing an audio track without re-encoding the video

Forum|Forum|11 years ago
October 20, 2014
1 reply
18945 views

I'm new to Audition CC so apologies for the basic question. I originally asked this in the Premiere Pro forum but I think it's more an Audition question.. I have AVCHD home video (MTS video with AC3 stereo audio) and have found I can clean up the audio, for example in speeches, very well in Audition. Is there a way to just replace the MTS's orginal audio track without re-encoding the video (which it seems I have to, if I do this via Premiere Pro)? In some cases the videos are poorly lit and any re-encoding makes them look noticeably worse than the original. In any event the video does not need re-encoding, I just need to replace the audio. Maybe I need to export the cleaned-up audio from Audition and use some other program to replace the audio in the original MTS file? Is that called re-muxing? Thanks in advance for any help.

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emmrecs

Legend

I don't have PP so can't be sure of this, but in the video editor I use the "audio" is always displayed as a separate "track" on the video editor screen. If I want to replace the camera audio I simply place the replacement audio, exported from Audition, on the next available track, ensuring it is correctly lined-up with the existing audio track (to ensure lip-sync etc.) and then either mute or delete the original audio. (Not sure about PP, but in my video editor I have first to "ungroup" the original audio from its video track to be able to delete it; once I am happy with the alignment of the "new" audio I will "group" this track with the video to ensure they stay locked together.)

O

Olly_

Participating Frequently

I have done that, by opening the MTS home video in Premiere Pro CC, selecting the clip in the Timeline, selecting 'Edit', 'Edit in Audition', 'Clip', which opens the audio track in Audition CC, where I clean it up and save, which returns me to Premiere Pro and I can play the combined result... the original video and the cleaned up audio track, which has replaced the original audio track. However it's the next step that foils me... To get a new MTS file with the new audio I have to save the changes, which re-encodes the video, which gives me a larger finished file with noticeably worse quality! So I'm starting to see that Premiere Pro can't do this. It has to re-encode the video as well as combining the new audio and I can't see any way to do that without video quality loss.

On a positive note I think there's a way that I'm still checking. I can drag the MTS straight into Audition, fix the audio, save the audio track as a new AC3 file (in my case checking it's 48khz, stereo, 16bit, 256kbps and Dolby Digital, not Dolby Digital Plus) and then use an open source program Avidemux to open the original MTS video, leave the main screen settings as Video Output..Copy, Audio Output..Copy, Output Format..MKV Muxer (not sure about this option, there may a better choice) and in the Audio menu..Select Track, in the Track 1 dropdown..Add Audio Track, then OK, play to check it's OK, and Save as a new MKV video file. The change in container from MTS to MKV seems OK and there's no video re-encoding. It's very quick, there's no video quality loss, the new audio is seamless and in-synch, the final file size is very similar to the original, and 'Media Info' shows the key internal video and audio specs are the same as in the original MTS video. I'll test some more and see if there are issues I haven't seen yet (I've only done one video so far).

sbekin01Author

Participant

I'd be surprised if Premiere Pro can't re-mux without re-encoding the video. But you will have to ask on the Premiere forum about that one.

Thanks emmrecs and ryclark.

emmrecs, Since my last post I also found tsMuxer and it's great. I use it to replace the original MTS video's AC3 audio track with one I've cleaned up in Audition, without re-encoding the video, so it's fast and no video quality change. I previously mentioned using Avidemux for this but later found it seems to drop the odd frame at the start when replacing an audio track, whereas tsMuxer does it perfectly. I'd also use it as you say to join MTS videos but mostly I need to cut and join, for which I'm finding Smart Cutter ($40) works very well; it 'smart renders' just a few frames around any cuts, with perfect joins, is fast, and with no overall video quality change.

ryclark, I have been Googling and asking on the Adobe Premiere Pro forum but I do not believe it can re-mux a replacement audio track. It has to re-encode the video as well, which is slow and I end up with a bigger file and worse video quality, so that's out for me. It also can't smart-render the way Smart Cutter does. It has to re-encode the whole video, again not what I need. With the non-Premiere Pro workflow I now have, including using MkvMerge as a last step (also no video re-encode), I get the new audio and trimmed/joined MKV videos, fast and with no overall video change.

On a general point, if I have to make a video smaller, to put on a social website, from what I've seen (not much really, I'm still new at this) I'll use Handbrake, not Premiere Pro. It's simpler and has great reviews for getting optimal quality/size. Compared to that, Premier Pro CC seems arcane, with having to somehow know the best settings for the Project, Sequence and whatever other Adobe program does the actual re-encoding. With no re-mux, smart-render or simple best-quality downsizing, all I'm currently using Premiere Pro for is to play/scrub videos to decide on cut/join points (it's hardware acceleration is great). Later maybe I'll experiment in Premiere Pro with micro-contrast, contrast, brightness and sharpen effects, which I know will mean I'll have to re-encode the video, so I think I'll only rarely do that; the videos straight out of my Sony vidcam are pretty good for my purposes.

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