# Overhead HLS **URL:** \ **Category:** Wowza Streaming Engine\ **Created:** [February 16, 2012, 5:40pm UTC](https://community.wowza.com/t/overhead-hls/36694 "2012-02-16T17:40:30Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![David\_Karlsson](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@David\_Karlsson](https://community.wowza.com/u/David_Karlsson)\ **Post date:** [February 16, 2012, 5:40pm UTC](https://community.wowza.com/t/overhead-hls/36694/1 "2012-02-16T17:40:30Z")
Hi. If you have an mp4 at lets say 40k/bits. What kind of overhead can you expect when playing it back as an HLS stream? From what it looks like (server v2.2.x) it adds almost 40-45 K/bits. Is that to be expected? That would mean that you would need to have the file at 20 K/bits to pass the app store inspection (lowest stream must be below 64 K/bit). Do wowza support an .aac as source and play it back as HLS? Just trying to figure out how to get such a low bitrate stream that will actually pass the apple inspection. BR //D ---
**Author:** ![Richard\_Lanham](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard\_Lanham](https://community.wowza.com/u/Richard_Lanham)\ **Post date:** [February 16, 2012, 10:38pm UTC](https://community.wowza.com/t/overhead-hls/36694/2 "2012-02-16T22:38:12Z")
There should be little or no added bandwidth usage to the network. The process of creating chunks for Cupertino streams adds some overhead to the server: memory use Richard ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 17, 2012, 4:54am UTC](https://community.wowza.com/t/overhead-hls/36694/3 "2012-02-17T04:54:47Z")
If you do audio only. Which is what is suggested here then the overhead is very, very small since we deliver using AAC packets rather than TS: [https://www.wowza.com/docs/how-to-create-apple-app-store-compliant-streams](https://www.wowza.com/docs/how-to-create-apple-app-store-compliant-streams) Charlie ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 19, 2012, 6:46am UTC](https://community.wowza.com/t/overhead-hls/36694/4 "2012-02-19T06:46:54Z")
We do not support raw AAC files. Only AAC in an MP4 container. Our TS implementation does not group video frames into a single logical PES packet which would improve the overhead. It is something we may add in the future. This is what leads to the overly high overhead. Charlie ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 19, 2012, 12:00pm UTC](https://community.wowza.com/t/overhead-hls/36694/5 "2012-02-19T12:00:27Z")
Again, it is something we will most likely improve in a future version. Charlie ---
**Author:** ![David\_Karlsson](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@David\_Karlsson](https://community.wowza.com/u/David_Karlsson)\ **Post date:** [February 17, 2012, 8:03am UTC](https://community.wowza.com/t/overhead-hls/36694/6 "2012-02-17T08:03:05Z")
Thank you for your reply. The cost of the ts container is usually around 20 K/bits at the 64K/bit in the scenarios when I´ve done this with true HLS streams (presegmented files). From the wowza I saw almost the double, so that´s why I asked. Is there some tuning that can be done to get the overhead down? How about delivering an audio only .aac file as the lowest stream? Is it possible? //D ---
**Author:** ![David\_Karlsson](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@David\_Karlsson](https://community.wowza.com/u/David_Karlsson)\ **Post date:** [February 19, 2012, 2:00pm UTC](https://community.wowza.com/t/overhead-hls/36694/7 "2012-02-19T14:00:26Z")
> If you do audio only. Which is what is suggested here then the overhead is very, very small since we deliver using AAC packets rather than TS: > > [Create streams compliant with Apple App Store](https://www.wowza.com/docs/how-to-create-apple-app-store-compliant-streams) > > Charlie Thank you Charlie. I tested it with an audio only aac file within an mp4 container and that seems to work with very little overhead. I couldn´t get it to use a .aac file as a source though. Getting back to the large overhead I saw, yes I did test it with a “crappy low res, low fps” A/V source. Is the 35-40K/bits to be expected from the wowza? Just thinking about the sub 128 K/bit stream the customer needs as well and if we need to keep the actual A/V below 90 K/bits in that case? (Easy to tes, but just to make sure we haven´t done anything stupid with our setup). BR /D ---
**Author:** ![David\_Karlsson](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@David\_Karlsson](https://community.wowza.com/u/David_Karlsson)\ **Post date:** [February 19, 2012, 8:52pm UTC](https://community.wowza.com/t/overhead-hls/36694/8 "2012-02-19T20:52:51Z")
> We do not support raw AAC files. Only AAC in an MP4 container. > > Our TS implementation does not group video frames into a single logical PES packet which would improve the overhead. It is something we may add in the future. This is what leads to the overly high overhead. > > Charlie Ah, ok so thats why I saw the extensive overhed. For streams over 500K/bits I wouldn´t care that much, it´s just for the low bandwidth stuff it might become troublesome. Thank you for your explanation. BR //D