Replacing audio and preserving video 1:1

Discussion in 'Digital Video' started by serr, Apr 10, 2017.

  1. serr macrumors regular

    Mar 8, 2010
    I'm an experienced audio engineer but nearly 100% clueless with video! I'd like to see someone talk about how to keep already lossy video 1:1 with the original. Preparing audio for bluray seems to ironically be the easy one these days. The different levels of lossy video formats are the confusing ones!

    How to preserve the video as is without re-encoding it?
    What video formats accept lossless PCM audio (max 48k is just fine in this example)?
    What ones require going to lossy audio? What lossy options do you get to choose from in this example?

    These are the questions that I get the 12-volt stare to.

    For example, if this was audio we would discuss how mp3 can be copied as a file 1:1 but decoding it back to wav and re-encoding it to mp3 would add another level of loss. Or how a 16 bit file can be put into a 24 bit format and preserved 1:1 but not the reverse.

    The mpeg-4/mov render option in Reaper of course re-encodes the video.

    What apps can be used to handle and keep intact the video component?

    Anyone know of a good reference chart for video? What formats can be put into what file container and what keeps things 1:1 vs. re-encoding?

    Today's task is this video file:
    Duration: 0:53:11
    Data Size: 1.46 GB
    Bit Rate: 3.92 Mbps
    Video Tracks:
    H.264, 960 × 540, 29.97 fps, 3.79 Mbps

    That info comes from MPEG Streamclip.
    This app lets you separate audio out and do some conversions (not all of which are clear) but has no function to replace a video file 1:1 with an original. Setting the output to 100% quality for example tries to produce a lossless format file (around 12GB) from the lossy source.

    I get that there might be some paid apps required. I get that some of this might be proprietary information. I'd sure appreciate it if someone could at least point me to some kind of cross reference chart or something though!

    PS. I am NOT looking for a critique of lossy formats like one might be tempted to offer for mp3. That's all useful info and well and good but I just want to know how to preserve any video 1:1 regardless of any format decisions made upstream.
  2. Booch21 macrumors regular


    Oct 13, 2010
    Hi! I'm a voice over guy, but won't claim to be an audio engineer. I fake it well enough!

    I dabble in video stuff myself and I am likely not to answer your question, but I'll make the attempt. When I record or acquire video, most of it is MP3 or WAV. When I'm recording, I was told to always record and edit/compile the video with 48K audio. In VO, I usually record 44.1K and it is just fine, but to match up the video with my audio, I'd be struggling to keep them lined up if I wasn't using 48K.

    Is Reaper your only source for working with the video? I use Adobe Premiere Pro for my video work and Audition for the audio work. I also have Final Cut but am not finding enough hours to work with it to use it proficiently. Because Premiere and Audition work hand in hand, I don't have issues when making the edits. They update right in my Premiere timeline as edited. I understand Audition *may* be able to do some basic video work, but I've never tried it, but it sounds similar to what you are trying to do with Reaper.

    Maybe Premiere Elements might be a way to go? It's inexpensive at $69.99 and might make things go smoother and less head scratching. As I said, I probably haven't answered your question at all, but thought my limited experience migt give you food for thought.
  3. serr thread starter macrumors regular

    Mar 8, 2010
    To be clear, I am not interested in editing or producing video in any way shape or form at this time. I only want to be able to preserve video handed to me that tags along with the audio I am tasked to work on.

    What I really want is a reference chart for formats and file containers. Not maybes or guesses but actual - formats A, B, & C fit into file containers X & Y 1:1. File container Z supports these audio formats: "..."

    Reaper is my one size fits all DAW app. It also includes cursory (and very incomplete) video support and does NOT include a way to preserve video files like I asked.

    I'd like to see a reference guide first. Then I might be armed with the info to choose apps as I needed them.
  4. ColdCase macrumors 68030

    Feb 10, 2008
    Maybe I'm not understanding what you are asking but to preserve the video, keep the original file. Don't do any transcoding whatever. Any transcoding is going to change something. If you are interested into whats the best file type to transcode to, thats mostly dependent on what the final distribution and delivery method will be.

    So I think you may be asking about the workflow where you are given a video with video and audio tracks. You want to adjust the audio without touching the video, or are you just removing the audio and working on it separately... never to meet up with the video again? So you want a product that can strip and perhaps add audio without affecting the video track.

    There are a few wiki pages that list what formats are supported by what containers. When I get back to a computer I can try to find those, although hopefully someone else jumps in here first.
  5. serr thread starter macrumors regular

    Mar 8, 2010
    Thanks ColdCase. Yeah, first is delivering the same video file format I was given (regardless of format) with the video itself unaltered but with new audio. I DO understand that exporting can involve re-encoding depending on the output format and that is precisely what I want to know how to avoid.

    I envision an app that you point to your original source video file and then your new audio file (edited to match up and all) and it just does it. Extra points if the default settings are no bs!

    Second would be a reference guide (to the extent such a thing is possible).

    I do know how to strip audio from video formats with zero loss at this point.
  6. jackerin macrumors 6502a

    Jun 29, 2008
    I know the MPEG-4 encoder in the old (version 7) Quicktime Pro allowed for audio/video passthrough, but I don't know if it works for all scenarios. Otherwise try looking for other video encoders that have a passthrough option.
  7. organicCPU macrumors 6502a


    Aug 8, 2016
    Your idea is a stream copy of video while exchanging the audio stream. You'd need to demux and mux without decoding and encoding the video stream, add your audio source and pack it again into a container format. If you have a H.264 (MPEG4-AVC), the video must stay in that compression untouched. Choose an appropriate container that fits to your audio and distribution needs, check it on native players as well as VLC Player. The tool that could work for your needs is ffmpeg.

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