Hi,
i would like to replace the audio track of an 8gig .MP4 video file and keep the same file size. At the moment when i go to export the movie with the new audio the resulting video file is 3 times as big. The original file is 1920 x 1080 at 25fr so i cant understand what is causing the massive increase in file size. I am new to the world of video FYI - go easy :)
best,
Garfield
Hi and welcome to the forum.
Without more information on your source video files and the export preset you are using - see this topic for where to get MediaInfo and the information to post, the most likely cause is that the source video is more compressed than the exported video.
John EB
Forum Moderator
Hi and welcome to the forum.
Without more information on your source video files and the export preset you are using - see this topic for where to get MediaInfo and the information to post, the most likely cause is that the source video is more compressed than the exported video.
John EB
Forum Moderator
Hi John,
many thanks for the welcome and help.
Is there a way to simply replace audio in a video without having to re encode?
I downloaded mediainfo and here is the result -
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (mp41/iso2/isom)
File size : 8.19 GiB
Duration : 1 h 59 min
Overall bit rate mode : Variable
Overall bit rate : 9 836 kb/s
Encoded date : UTC 2020-02-02 19:25:18
Tagged date : UTC 2020-02-02 19:25:18
Video
ID : 2
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4
Format settings : CABAC / 1 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 1 frame
Format settings, GOP : M=1, N=50
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1 h 59 min
Bit rate mode : Variable
Bit rate : 9 624 kb/s
Maximum bit rate : 10 000 kb/s
Width : 1 920 pixels
Clean aperture width : 1 888 pixels
Height : 1 080 pixels
Clean aperture height : 1 062 pixels
Display aspect ratio : 16:9
Clean aperture display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.186
Stream size : 8.01 GiB (98%)
Language : English
Encoded date : UTC 2020-02-02 19:25:18
Tagged date : UTC 2020-02-02 19:25:18
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : avcC
Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 1 h 59 min
Source duration : 1 h 59 min
Bit rate mode : Constant
Bit rate : 197 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 165 MiB (2%)
Source stream size : 165 MiB (2%)
Language : English
Encoded date : UTC 2020-02-02 19:25:18
Tagged date : UTC 2020-02-02 19:25:18
I cant see how to output the same size file in MEP?
Best,
Adam
Hi Adam
Thanks for the MediaInfo analysis.
The source file is highly compressed with a video bit rate of 9,836 kb/s compared to the standard MP4 1920x1080 25fps export preset which has an average video bit rate of 22 000 kbs to a max of 28000 kbs.
The difference will give you an approximate doubling in file size - is this what you are seeing?
Is there a way to simply replace audio in a video without having to re encode?
Not without re-encoding, you would have to change the video bit rate, in the export setting,to a similar value to the source video - under the Advanced button in the export dialog.
However this will result in the quality dropping and potentially blockiness appearing in the final video.
Unless it is absolutely essential to have the file size so small, I would advise against dropping the video bit bitrate.
HTH
John EB
Can you do a similar text output from Media Info from the original clip please?
I'm wondering if the original file was recorded in H265.
Hi Adam
Thanks for the MediaInfo analysis.
The source file is highly compressed with a video bit rate of 9,836 kb/s compared to the standard MP4 1920x1080 25fps export preset which has an average video bit rate of 22 000 kbs to a max of 28000 kbs.
The difference will give you an approximate doubling in file size - is this what you are seeing?
Is there a way to simply replace audio in a video without having to re encode?
Not without re-encoding, you would have to change the video bit rate, in the export setting,to a similar value to the source video - under the Advanced button in the export dialog.
However this will result in the quality dropping and potentially blockiness appearing in the final video.
Unless it is absolutely essential to have the file size so small, I would advise against dropping the video bit bitrate.
HTH
John EB
Hi John,
yes it is about double the size so that makes sense. I think Premiere has a "match original" preset in its settings. Not sure what that does exactly but if the quality of the video remains the same could be a nice feature.
The smaller size is a convenience rather that an absolute, so i will use the HD mp4 preset.
Many thanks for your assistance,
best regards!
Can you do a similar text output from Media Info from the original clip please?
I'm wondering if the original file was recorded in H265.
Hi,
i dont have the original file. Just the compressed .MP4 that needs the audio replacing.
best!
Unless it is absolutely essential to have the file size so small, I would advise against dropping the video bit bitrate.
What John said is true to a point but you could try setting the video bitrate in the advanced export window to something smaller - say 15000kbps or less and see how it looks.