# Is an RTMP stream with h264 video transcoded on Wowza HLS output or passed through (assuming the transcoder is disabled) **URL:** \ **Category:** Wowza Streaming Engine\ **Created:** [June 13, 2022, 2:21pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055 "2022-06-13T14:21:32Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Dan\_Farrow](https://avatars.discourse-cdn.com/v4/letter/d/bb73d2/32.png) [@Dan\_Farrow](https://community.wowza.com/u/Dan_Farrow)\ **Post date:** [June 13, 2022, 2:21pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/1 "2022-06-13T14:21:33Z")
If I send an RTMP stream with 4k@30fps 12000 Kbps data H264 encoded with the Wowza transcoder system **disabled** , do I get the exact same output in my HLS files as the input (the identical 12000 Kbps H264 bytes)? I want to know if there is there any kind of transcoding happening during in the conversion from RTMP to HLS? If there is transcoding process happening, how do I control the bitrate of this HLS output. I see there is an app property “cupertinoDefaultVideoBitrate” with a default of 250000, so it seems this is controllable? ---
**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\ **Post date:** [June 13, 2022, 7:53pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/2 "2022-06-13T19:53:35Z")
asking for you @Dan_Farrow… ---
**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\ **Post date:** [June 13, 2022, 8:03pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/3 "2022-06-13T20:03:58Z")
It’s my understanding that Passthrough streams are not transcoded but they may be repackaged—for example: Wowza may receive an H.264 RTMP stream and apply an HLS wrapper around it for delivery. Passthrough streams ingest a single encode and deliver a single output rendition whose video and audio bitrate, H.264 profile, frame rate, aspect ratio, and keyframe interval match those of the ingested source. But, I’ll confirm with tech support. ---
**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\ **Post date:** [June 13, 2022, 8:10pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/4 "2022-06-13T20:10:24Z")
Tech Support: “I am not aware of any option to reduce the bitrate without transrating the source for output.” ---
**Author:** ![Dan\_Farrow](https://avatars.discourse-cdn.com/v4/letter/d/bb73d2/32.png) [@Dan\_Farrow](https://community.wowza.com/u/Dan_Farrow)\ **Post date:** [June 13, 2022, 11:44pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/5 "2022-06-13T23:44:50Z")
So it sounds like what goes in is what comes out, unless you do transcoding? Is that correct? ---
**Author:** ![Connessione](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Connessione](https://community.wowza.com/u/Connessione)\ **Post date:** [June 18, 2022, 9:06pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/6 "2022-06-18T21:06:12Z")
I believe it is something like transmuxing here. **Transcode is converting from one codec to another, maybe something more common.**** Transmux (transcode-multiplexing) is converting to a different container format, but keeping the file contents the same** ---
**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\ **Post date:** [June 21, 2022, 4:45pm UTC](https://community.wowza.com/t/is-an-rtmp-stream-with-h264-video-transcoded-on-wowza-hls-output-or-passed-through-assuming-the-transcoder-is-disabled/95055/7 "2022-06-21T16:45:38Z")
## So, What Is Transcoding? First, the word _transcoding_ is commonly used as an umbrella term that covers several digital media tasks: - _ **Transcoding** _ , at a high level, is taking already compressed (or encoded) content; decompressing (decoding) it; and then somehow altering and recompressing it. As an example, you might change the audio and/or video format ([codec](https://www.wowza.com/blog/video-codecs-encoding)) from one to another, such as converting from an MPEG2 source (commonly used in broadcast television) to [H.264](https://www.wowza.com/blog/video-codecs-encoding#H264) [video](https://www.wowza.com/blog/video-codecs-encoding) and [AAC](https://www.wowza.com/blog/best-audio-codecs-live-streaming#AAC) [audio](https://www.wowza.com/blog/best-audio-codecs-live-streaming) (the most popular codecs for streaming). Other basic tasks could include adding watermarks, logos, or other graphics to your video. - _ **Transrating** _ refers specifically to changing bitrates, such as taking a 4K video input stream at 13 Mbps and converting it into one or more lower-bitrate streams (also known as renditions): HD at 6Mbps, or other renditions at 3 Mbps, 1.8 Mbps, 1 Mbps, 600 kbps, etc. - _ **Transsizing** _ refers specifically to resizing the video frame, say, from a resolution of 3840×2160 (4K UHD) down to 1920×1080 (1080p) or 1280×720 (720p). So, when you say _“transcoding,”_ you might be referring to any combination of the above tasks — and typically are. * * * **## What Transcoding Is _Not_** Transcoding should not be confused with _transmuxing_ , which can also be referred to as _repackaging_ , _packetizing,_ or _rewrapping_ . Transmuxing is when you take compressed audio and video and — without changing the actual audio or video content — (re)package it into different delivery formats. For example, you might have H.264/AAC content, and by changing the container it’s packaged in, you can deliver it as [HTTP Live Streaming (HLS)](https://www.wowza.com/blog/hls-streaming-protocol) or [Dynamic Adaptive Streaming over HTTP (DASH)](https://www.wowza.com/blog/mpeg-dash-dynamic-adaptive-streaming-over-http). The computational overhead for transmuxing is much smaller than for transcoding. * * * Hope that helps you @Dan_Farrow