<p>Your split files are smaller because they are being recompressed.</p>
<p>The split files have a bit-rate of 75.9 kbps.</p>
<p>The original file had a bit-rate of 7,577 kbps.</p>
<p>Optimise this by deciding what bit-rate you need to record at. This will be a trade off between file size and image quality needed.</p>
<p>Check the amount of free space left on your drive before you record.</p>
<p>Use a <a href="https://toolstud.io/video/filesize.php?width=1920&amp;height=1080&amp;framerate=25&amp;timeduration=60&amp;timeduration_unit=seconds&amp;compression=19290&amp;specificbitrate=100&amp;specificbitrate_unit=1000000" rel="nofollow noreferrer">video file size calculator</a> to work out how much space your recordings will take up.</p>
<p>Bear in mind that other apps and your OS may use some space over time on the drive to swap files etc.</p>

CC BY-SA 4.0
2023-03-02T15:18:47.270Z
2023-03-02T15:18:47.270Z
tomh
<p>Sorry I do not give better details, I am too new on this</p>
<p>this weekend we left OBS recording a small portion of the screen, with audio, for an university experiment (we have a software that analize noise, but lacks video record)</p>
<p>today I got a 12 GB file for 11 hours 27 mins, and a space disk error (yep, we were short of space)</p>
<p>acording Media Info, file settigns are:</p>
<pre><code>Gneral
Complete name                            : N:\File.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 12.4 GiB
Duration                                 : 11 h 27 min
Overall bit rate                         : 2 577 kb/s
Writing application                      : Lavf58.76.100
Writing library                          : Lavf58.76.100
ErrorDetectionType                       : Per level 1

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L2
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 11 h 27 min
Nominal bit rate                         : 2 500 kb/s
Width                                    : 192 pixels
Height                                   : 108 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 10.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 12.056
Writing library                          : x264 core 163 r3060 5db6aa6
Encoding settings                        : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=3 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=250 / keyint_min=10 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=cbr / mbtree=1 / bitrate=2500 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=2500 / vbv_bufsize=2500 / nal_hrd=none / filler=1 / ip_ratio=1.40 / aq=1:1.00
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : A_AAC-2
Duration                                 : 11 h 27 min
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Title                                    : simple_aac
Default                                  : Yes
Forced                                   : No
</code></pre>
<p>as analizing the file by one person is too much, I split in files, with MKVToolNix, and due to creation time, I chose: 01:04:45,04:04:45,07:04:45,10:04:45  (first and last are shorter, other 3 files are 3 hours long).  MKVToolNix suposelly split the file WITHOUT recodification.</p>
<p>SURPRISE, output file are 40MB, 3 of 100MB, and last of 45 MB, total 375 MB instead of 12 GB</p>
<p>I got details for the second file:</p>
<pre><code>General
Complete name                            : D:\File-002.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 97.8 MiB
Duration                                 : 3 h 0 min
Overall bit rate                         : 75.9 kb/s
Encoded date                             : UTC 2023-02-27 16:15:19
Writing application                      : mkvmerge v60.0.0 ('Are We Copies?') 64-bit
Writing library                          : libebml v1.4.2 + libmatroska v1.6.4 / Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L2
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 3 h 0 min
Bit rate                                 : 1 246 b/s
Width                                    : 192 pixels
Height                                   : 108 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 10.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.006
Stream size                              : 1.60 MiB (2%)
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : A_AAC-2
Duration                                 : 3 h 0 min
Bit rate                                 : 73.5 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Delay relative to video                  : 5 ms
Stream size                              : 94.6 MiB (97%)
Title                                    : simple_aac
Default                                  : Yes
Forced                                   : No
</code></pre>
<p>Not sure what has happend, why the file stop after 11 hours, why it takes so much space, and why the splited files are much lower size</p>
<p>may somebody help us??
(we need to repeat the experiment, and we need the recording to last for 72 hours straigh)</p>

<audio><video-quality><video-recording><audio-recording><recording>
Recording webcam got too big file in 12 hours, spliting the file takes much less space
Carlos Tiel
# Recording webcam got too big file in 12 hours, spliting the file takes much less space

(Asked by: username_0 on 2023-02-27)

Sorry I do not give better details, I am too new on this
this weekend we left OBS recording a small portion of the screen, with audio, for an university experiment (we have a software that analize noise, but lacks video record)
today I got a 12 GB file for 11 hours 27 mins, and a space disk error (yep, we were short of space)
acording Media Info, file settigns are:
Gneral
Complete name                            : N:\File.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 12.4 GiB
Duration                                 : 11 h 27 min
Overall bit rate                         : 2 577 kb/s
Writing application                      : Lavf58.76.100
Writing library                          : Lavf58.76.100
ErrorDetectionType                       : Per level 1

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L2
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 11 h 27 min
Nominal bit rate                         : 2 500 kb/s
Width                                    : 192 pixels
Height                                   : 108 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 10.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 12.056
Writing library                          : x264 core 163 r3060 5db6aa6
Encoding settings                        : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=3 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=250 / keyint_min=10 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=cbr / mbtree=1 / bitrate=2500 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=2500 / vbv_bufsize=2500 / nal_hrd=none / filler=1 / ip_ratio=1.40 / aq=1:1.00
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : A_AAC-2
Duration                                 : 11 h 27 min
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Title                                    : simple_aac
Default                                  : Yes
Forced                                   : No

as analizing the file by one person is too much, I split in files, with MKVToolNix, and due to creation time, I chose: 01:04:45,04:04:45,07:04:45,10:04:45  (first and last are shorter, other 3 files are 3 hours long).  MKVToolNix suposelly split the file WITHOUT recodification.
SURPRISE, output file are 40MB, 3 of 100MB, and last of 45 MB, total 375 MB instead of 12 GB
I got details for the second file:
General
Complete name                            : D:\File-002.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 97.8 MiB
Duration                                 : 3 h 0 min
Overall bit rate                         : 75.9 kb/s
Encoded date                             : UTC 2023-02-27 16:15:19
Writing application                      : mkvmerge v60.0.0 ('Are We Copies?') 64-bit
Writing library                          : libebml v1.4.2 + libmatroska v1.6.4 / Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L2
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 3 h 0 min
Bit rate                                 : 1 246 b/s
Width                                    : 192 pixels
Height                                   : 108 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 10.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.006
Stream size                              : 1.60 MiB (2%)
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : A_AAC-2
Duration                                 : 3 h 0 min
Bit rate                                 : 73.5 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Delay relative to video                  : 5 ms
Stream size                              : 94.6 MiB (97%)
Title                                    : simple_aac
Default                                  : Yes
Forced                                   : No

Not sure what has happend, why the file stop after 11 hours, why it takes so much space, and why the splited files are much lower size
may somebody help us??
(we need to repeat the experiment, and we need the recording to last for 72 hours straigh)

**Tags:** audio, video-quality, video-recording, audio-recording, recording


---

## 1 answers

### Answer by username_1 on 2023-03-02. Score: 0

Your split files are smaller because they are being recompressed.

The split files have a bit-rate of 75.9 kbps.

The original file had a bit-rate of 7,577 kbps.

Optimise this by deciding what bit-rate you need to record at. This will be a trade off between file size and image quality needed.

Check the amount of free space left on your drive before you record.

Use a [video file size calculator](https://toolstud.io/video/filesize.php?width=1920&height=1080&framerate=25&timeduration=60&timeduration_unit=seconds&compression=19290&specificbitrate=100&specificbitrate_unit=1000000) to work out how much space your recordings will take up.

Bear in mind that other apps and your OS may use some space over time on the drive to swap files etc.


---

