Most references describe 128 kbps as "near CD quality". When compared to a CD, one website evaluated 128 kbps this way: "At 128 kbps certain blemishes started to show through quite clearly, most noticeably on the drum hi hat cymbals. These had a very processed, artificial, sound. Vocals started to sound a bit metallic, and the whole recording sounded harsh."
Currently, Off the Charts encodes its JTV stream at 192 kbps. Whenever possible, the source material, i.e., the music I play, is ripped at the highest variable bitrate supported by MP3. The quality of the source reproduction determines the number of bits needed for the file. A Glenn Miller recording from the 40s might require about 120 kbps to maximally encode into MP3. A CD of Five Man Electrical Band recordings from the 70s averaged around 210 kbps. A Best of Sarah McLaughlin CD ripped at about 240 kbps. These are averages since the bit rate is variable.
My number one priority with the Off the Charts stream is to provide an excellent audio experience. I appreciate clean, accurate music reproduction, and i think many Off the Charts viewers do, too. To that end, I wrote to Dylan today to see if there is any wiggle room in their new specifications:
Hi Dylan,
I have 1 question I hope you can answer for me. Regarding lowering the maximum MP3 audio bit rate to 128kbps, is this something JTV is CHOOSING to do, or is it something JTV MUST do because of the tool or product you are using in order to get the increased number of channels to show on the mobile devices?
Background: I cast at 192 kbps audio. Jake says he casts at 160 kbps. Probably other people cast at audio bit rates above 128. If I have to drop my audio bit rate by 1/3rd, I think my audio stream will be of noticeably lower quality for SOME of my viewers who are using high quality headphones or other higher-end audio gear. My audio quality is my top concern for my channel. I do everything I can within my limited budget to provide the best audio for my listeners/viewers. You said you are not an audio guy. Well, I am an audio guy and some of my listeners are, too.
I would use AAC audio at 160 kbps if I could, but Adobe FME doesn't offer AAC encoding. Other webcasting software that does offer AAC is either too expensive and/or won't run on my older Win XP PC.
I notice JTV isn't limiting the video bit rate, only the audio.
Is there any way the MP3 maximum could be made the same as the AAC maximum, 160 kbps? That rate would be acceptable while providing discerning listeners with a better experience. You said in Community Chat that JTV tries to keep its casters happy. Hopefully, this will be one case where that comes true.
Thanks,
"Gil"
Update August 21:
Hey Gil,
I'll ping our video team about this and see if I can find out. I know that they really prefer AAC, but still wanted to support MP3 as it is widely used. I think there is a way to get AAC on Flash Media Encoder on a new configuration profile we have going out. I'll let you know when that's available.
Regards,
Dylan Reichstadt
By the way, AAC is technically superior to MP3. I'd use it if I could.