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LiveStreamRecord - CFR(Constant Frame Rate) Mode


I’m developing LiveStreamRecord Application to record a live.

I can record videos on mp4 correctly.

But mp4 file is VFR frame rate mode.

Is it possible to change CFR frame rate mode?



Hello there,

Wowza records what is sent in. You can use the Wowza Transcoder to achieve a consistent frame rate (as well as many other features):

How to set up and run Wowza Transcoder AddOn for live streaming

Wowza Transcoder AddOn Overview


Hi Kato,

Is the file a problem to use in anyway?

Looking at a file recorded with Wowza HTTPLiveStreamRecord (but not a Transcoder rendition) with MediaInfo I see the same lines. These were from a recording made from mpeg-ts stream produced by VLC

Frame rate mode : VFR

Frame rate mode : Variable

Frame rate : 23.212

Frame rate : 23.212 fps

Original frame rate : 24.000

Original frame rate : 24.000 fps

Minimum frame rate : 11.905

Minimum frame rate : 11.905 fps

Maximum frame rate : 24.390

Maximum frame rate : 24.390 fps

But when I playback the same file in RTMP client in Flash Builder, the onMetaData I see “videoframerate = 23.80952380952381”

FFprobe reported 23.21 fps for the same stream.

I cannot account for the slight difference in the reports of these 3rd party tools, but they agree closely.

In a recording made from FMLE with 15ps and Key frame Frequency set to 3 seconds, the lines are the same but the range is much narrower:

Frame rate mode : VFR

Frame rate mode : Variable

Frame rate : 15.026

Frame rate : 15.026 fps

Original frame rate : 15.000

Original frame rate : 15.000 fps

Minimum frame rate : 13.699

Minimum frame rate : 13.699 fps

Maximum frame rate : 16.129

Maximum frame rate : 16.129 fps

I also looked at recording from Wowza Transcoder renditions and it had similar info in MediaInfo. And I tried a recording with a template /Encode /KeyFrameInterval /FollowSource set to “false” on the VLC stream, but that no affect on the data shown in MediaInfo, it was the same range.


Has a solution to this been found? I’m streaming a file in Constant Frame Rate to Wowza, but Wowza records it to Variable Frame Rate. Is there a way to “force” it record in CBR?



Hello Savadore,

Thank you for reply,

Environment I’m using is as follows.

Regardless of the transcoding, Our problem is to be a VFR mode. Because our Filebase transcoder does not work correctly.

Therefore I would like to change CFR frame rate mode.

Any ideas?


Sony IPCamera: SNC-VB630(

Source Video Info:

Codec: H.264

Resolution: 1920x1080 High@L4.1

Framerate: 30 fps

BitrateMode : CBR

Bitrate : 8Mbps


Protocol: RTSP


[Wowza Record File(Information using MediaInfo)]


name : vb630.stream_720p.mp4

Format : MPEG-4

Format profile : Adobe Flash

Codec ID : f4v

File size : 26.4 MiB

Duration : 1Min 22Sec

Overall bit rate mode : VBR Mode

Overall bit rate : 2 688 Kbps

Video Info

ID : 1

Format : AVC

Format/Info : Advanced Video Codec

Format profile : Main@L3.1

Format settings, CABAC : Yes

Format settings, ReFrames : 3 Frames

Format settings, GOP : M=1, N=60

Codec ID : avc1

Codec ID/Info : Advanced Video Coding

Duration : 1Min 22Sec

Bit rate mode : VBR mode

Bit rate : 2 589 Kbps

Maximum bit rate : 1 430 Kbps

Width : 1280

Height : 720

Display aspect ratio : 16:9

** Frame rate mode : VFR Mode **

** Frame rate : 29.970 fps **

** Original frame rate : 14.990 fps **

** Minimum frame rate : 29.412 fps **

** Maximum frame rate : 30.303 fps **

Standard : NTSC

Color space : YUV

Chroma subsampling : 4:2:0

Bit depth : 8 bit

Scan type : Progressive(PPF)

Bits/(Pixel*Frame) : 0.094

Stream size : 25.5 MiB (96%)

Title : WowzaStreamingEngine

Thanks in advance.


Same here.

Encoder send CFR 50 and the downloaded file looks like:

Frame rate mode : Variable
Frame rate : 50.000 FPS
Minimum frame rate : 47.619 FPS
Maximum frame rate : 52.632 FPS