62
You can use ffmpeg to create video from audio using several filters.
ahistogram
Convert input audio to a video output, displaying the volume histogram.
ffmpeg
ffmpeg -i input.flac -filter_complex \
"[0:a]ahistogram,format=yuv420p[v]" \
-map "[v]" -map 0:a output.mp4
ffplay
ffplay -f lavfi "amovie=input.flac, asplit [a][out1]; [a] ahistogram [out0]"
...
24
#1 To simultaneously fade the audio in/out:
ffmpeg -i clip.mp4 -vf 'fade=in:0:30,fade=out:960:30'
-af 'afade=in:st=0:d=1,afade=out:st=32:d=1'
-c:v libx264 -crf 22 -preset veryfast fadeInOut.mp4
The afade times are in seconds.
#2 Automatically? No. But see workaround below
You can first run ffprobe to get duration.
ffprobe -i ...
23
There's a semi-automatic way to do this – semi automatic because it involves only typing three keystrokes over and over: xf,, xf,, xf,… — you could train your cat to do it!
Here's how it goes:
make sure the audio is enabled for the tracks you want to restore (you only need to do this once)
park the playhead over one of the clips.
hit x (for Mark Clip) to ...
17
The frames in your H.264 video are grouped into units called GOPs (Group Of Pictures). Inside these GOPs frames are classified into three types:
I-frame: frame that stores the whole picture
P-frame: frame that stores only the changes between the current picture and previous ones
B-frame: frame that stores differences with previous or future pictures
...
12
It's a terrible hack, but this might work if all you want to do is audio fade in/out but don't know exactly how long the clip is:
ffmpeg -i input.mp4 -filter_complex "afade=d=0.5, areverse, afade=d=0.5, areverse" output.mp4
[edit 2019-07-24: Note that this solution is not good for streaming solutions since it requires the full track to be processed before ...
10
Yes. MPEG-4 Part 14 (the MP4 container format) supports any number of objects (e.g. video, audio and subtitle streams) and isn't limited to only one stream per content type.
In practice however, you seldom see a video file that has multiple video streams, because the range of applications for this is very limited. I would also advise you not to put multiple ...
10
The usual solution for this situation: -fflags +genpts
It should eliminate the warning, but there's no guarantee your sync issues will be solved.
9
Run
ffmpeg -i titlefile.mp4 -vf setdar=16/9 -video_track_timescale 29971 -ac 1 newtitle.mp4
and then run concat with the new title video.
Modern containers like MP4 have Presentation TimeStamps, which are denominated with reference to a timebase. So, if the timebase value is 1/500 and a frame's PTS is 200, then that tells the video player to show that ...
8
There are a variety of reasons to have an external recorder depending on the size of your production. A big advantage is the number of audio inputs and the ability to record each of those inputs as separate tracks, allowing you to do the mixing in post. I'm not sure about the H4n, but I know the H5 and H6 support multiple inputs as well as interchangeable ...
8
FFmpeg's loudnorm filter can be used. Basic syntax is
ffmpeg -i in.mp4 -c:v copy -af loudnorm=I=-23:LRA=1 -ar 48000 out.mp4
The loudness range (LRA) should be 2 x max deviation.
Also see the ebur128 filter for measuring loudness.
6
You can use ffmpeg with the compand audio filter (a port of sox effect filter of same name) to "compress or expand the audio's dynamic range", but admittedly this is one of the more complicated audio filters.
Example from the documentation
Make music with both quiet and loud passages suitable for listening to in a noisy environment (whatever that ...
6
Back in the day when movie cameras recorded to film, the sound made by the cameras was something to be isolated from the sound recording process. Digital video cameras make very little noise (with the odd exception of things like early model RED cameras that needed high-powered fans to deliver sufficient cooling for their hot-rodded internals).
But that's ...
6
FFmpeg, a free command-line tool, has a volume filter that should do this.
Syntax would be
ffmpeg -i input.mp4 -c:v copy -af volume=replaygain=track output.mp4
The af invokes the volume filter with the option set to adjust the volume using the track replaygain value (if present). Video is set to passthrough into the output.
6
For video, stream_loop option should be used.
ffmpeg -y -stream_loop -1 -i video -i audio.mp3 -fflags +shortest -max_interleave_delta 50000 -c copy output.mp4
You'll have to use a very recent version of ffmpeg (> Nov '17) as stream_loop had a bug, only recently fixed.
Since video encoding is expensive in terms of time and CPU, I've used streamcopy. For ...
6
Most video encoders apply temporal compression i.e. most frames only store the difference in image content relative to other frames, thus saving storage space, while a few frames store the whole image. The frames with whole pictures are called key frames since they are required in order to reconstruct the whole picture of frames which only store differences. ...
5
It depends on the exact studio's process, but generally either an animatic (basically a roughly animated storyboard) or the audio is done first. In the case of Family Guy and American Dad specifically, it sounds like they work on the audio and the animatic first. The advantage to doing an animatic first is it can help the voice actors visualize what will ...
5
Is it possible? Sure, just setup each source clip as a sequence that has the audio feed you want for that shot and leave the tracks linked so that you cut between both video and audio.
Is it advisable? Probably not. People are far less used to changing of the audio scene they are watching. Video creates kind of a disconnect between the scene we are ...
5
Yes, its way better. Being able to monitor the levels, and headphones, makes a huge difference.
However, its not even just the quality of the mic or recording device its the location. Having an external recorder means you can separate the audio easily from the camera. Back in the day when I was a teen, and had more enthusiasm than money, we used mics from ...
5
Youtube generally reencodes all videos you upload to youtube to ensure compatibility across various platforms and to provide smaller versions of the videos for users with slow internet connections. So yes, both the video and the audio stream of your video file will be compressed and reencoded when you upload it. If someone uses a third party tool to download ...
5
First, get ffmpeg.
Generally, you want to give YouTube the highest quality you can because it will re-encode anything you give it, but the formats used in MXF can be mental for uploading. So re-encoding to modern formats for a more manageable upload often makes sense.
Example
ffmpeg -i input.mxf \
-filter_complex "[0:a:0][0:a:1]amerge" \
-ac 2 -c:v ...
5
The Mainconcept or Sony codecs in Vegas are subpar for low-bitrate output such as needed for HTML5 use. Use ffmpeg to generate your HTML5 videos. Yes, mono audio is acceptable for HTML5 use, but once you use ffmpeg/x264 for generating those videos, the 6kB/s savings you get from switching to mono audio won't matter much if at all.
Get the 32-bit static ...
5
ffmpeg, a free multi-platform command-line tool, can do this.
Use the volumedetect and EBUR filters on each of the files
ffmpeg -i input.mov -af volumedetect,ebur128 -f null - 2> input.log
This will produce a log file with the initial lines looking like this:
[Parsed_ebur128_1 @ 0000000002d42400] t: 12.7 M: -32.7 S: -32.7 I: -30.7 LUFS ...
5
First off, if you have audio with your video (that you want to replace with your high-quality audio recording), then step #1 is to nudge the Zoom audio track to line up the impulse of the clap with the corresponding impulse of the scratch audio from the video file. To do that, you need to change the Timecode Display Format to Audio Samples. Once you do ...
5
If you run ffmpeg -layouts, you will see that stereo indicates the presence of two channels, one assigned as Front Left and the other as Front Right. If you use -ac 2 in your encode, ffmpeg will create a stereo layout output by default. FFmpeg does not display the individual channel assignments in the readout of the file.
5
There are, in fact, several standards on audio/video or lip sync. The problem is, they can't all agree on what the acceptable error is. What is well understood is that if the audio lags the video it is less noticeable, because that is natural. Something that is further away will be seen before it is heard. In the list below, a negative number is the audio ...
5
It's generally preferred to use the actual dialog audio from the take. It matches the movement of the lips, it sounds right for the environment, the actor is giving an authentic performance, etc. And, you don't have to pay the actor to come back for an extra day re-recording audio in a rented sound booth.
"Looping" in audio after a scene is shot is ...
4
If you work on a regular basis with the "owner" of the voice I can recommend Nuance's Dragon it offers very accurate speech to text with very few errors but it needs some "calibration" to a specific voice.
So if you can get your actor/narrator to read the calibration text you will have an easy time making transcripts and subtitles (though subs will require ...
4
AVI and MKV are both containers, so in theory it should be possible to transfer your contents with no further loss. I can't say for certain if MKV can wrap xvid4, but it's very likely. You shouldn't need to decode / re-encode to transfer the contents, just demux / remux.
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