Turtlerock Forum

So...

We're converting some videos for a client to play off his iPhone, and plugging into a projector for a corporate show.

Essentially, we just wanted to see if we could get the video looking good enough on a big screen without any compression artefacts.

Anyway, turns out, the "Official" specs on the iPhone 5 allow it to play video at 62.5 MBit.
To put that into perspective, that's 25% better than the absolute best quality you can get from a BluRay player, most BluRay's are about 30-35 Mbit,

So Video quality is essentially double the quality that you get from a BluRay... and audio quality...

Yep... Audio Quality is limited to Stereo 160 Kbit AAC. Regardless of what you set the video too.

I just don't get how video standards have been increasing, but audio standards have been decreasing?

Even Bloody DVD has better quality sound !!

#EndRant

Simon "Smash" Ashby

160 is considered high res by apple

Facepalm

I have just been invited to join ( and put on) Apples mastering for iTunes providers list .. it is very clear to me that apple DO give a f@#$ about sound quality and that any format changes however big or small they make to their iOS stuff
must be a major headache to implement ..
outside the regular pay check I wouldn't want to work for apple in a million years .. the difference between what they can do , what they need to do and what they should do would just fry my noodle ..

So your lil Iphone makes and takes videos and sound ...?
Come on smash ..its kinda science fiction really..
the original star-trek models just had sound ..no pictures.

there is nothing really stupid about their smart phones except the damn phone part barely works long enough for a full conversation

As a quick test I transcoded a 3 second clip to mp4, was able to transfer it to my iPhone 5 and watch it. Maybe look at using different software to do the conversion? I was unable to get higher than 256kbps audio to encode though.

Details below.

===================== General =====================
Complete name : D:\music videos\Brutal Truth - Collateral damage_3.mp4
Format : MPEG-4
Format profile : Base Media
Codec Id : isom
File size : 863 KB
Duration (ms) : 3s 42ms
OverallBitRate_Mode/String : Variable
Total bitrate : 2 324 Kbps
Encoded application : Lavf54.61.104

===================== Video =====================
Id : 1
Format : AVC
Format info : Advanced Video Codec
Format profile : High@L3.1
Use of CABAC : Yes
RefFrames : 4 frames
Codec Id : avc1
Codec info : Advanced Video Coding
Duration (ms) : 3s 0ms
Bitrate : 2 125 Kbps
BitRate_Nominal/String : 2 000 Kbps
Width : 720 pixels
Height : 588 pixels
Aspect ratio : 1.222
Framerate mode : Constant
Framerate : 25.000 fps
Colorimetry : YUV
Colos space : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.201
Stream size : 778 KB (90%)
Encoded library : x264 core 129 r2245 bc13772
Encoded library settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / 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=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=2000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00

===================== Audio =====================
Id : 2
Format : AAC
Format info : Advanced Audio Codec
Format profile : LC
Codec Id : 40
Duration (ms) : 3s 42ms
Bitrate mode : Variable
Bitrate : 219 Kbps
Bitrate maximum : 256 Kbps
Channel(s) : 2 channels
ChannelPositions : Front: L R
Sampling rate : 44.1 KHz
Compression_Mode/String : Lossy
Video_Delay/String : 80ms
Stream size : 81.3 KB (9%)

smash wrote:So...

We're converting some videos for a client to play off his iPhone, and plugging into a projector for a corporate show.

Essentially, we just wanted to see if we could get the video looking good enough on a big screen without any compression artefacts.

Anyway, turns out, the "Official" specs on the iPhone 5 allow it to play video at 62.5 MBit.
To put that into perspective, that's 25% better than the absolute best quality you can get from a BluRay player, most BluRay's are about 30-35 Mbit,

So Video quality is essentially double the quality that you get from a BluRay... and audio quality...

Yep... Audio Quality is limited to Stereo 160 Kbit AAC. Regardless of what you set the video too.

I just don't get how video standards have been increasing, but audio standards have been decreasing?

Even Bloody DVD has better quality sound !!

#EndRant

Simon "Smash" Ashby

Kurt wrote:As a quick test I transcoded a 3 second clip to mp4, was able to transfer it to my iPhone 5 and watch it. Maybe look at using different software to do the conversion? I was unable to get higher than 256kbps audio to encode though.

It's interesting - we can literally use whatever settings we want, so as a test I used a bitrate of 380 Kbit - and it worked totally fine without any issues. The only thing that I question is that if Apple says that it only works at 160 Kbit, what can go wrong if we use a higher rate, i.e. will it work in some situations, but not in others?

Simon "Smash" Ashby

Maybe it's only guaranteed for smooth playback up to the standard setting on all iDevices? For example, maybe an iPhone 4S doesn't have the processing power to play back a higher specced file?

smash wrote:

Kurt wrote:As a quick test I transcoded a 3 second clip to mp4, was able to transfer it to my iPhone 5 and watch it. Maybe look at using different software to do the conversion? I was unable to get higher than 256kbps audio to encode though.

It's interesting - we can literally use whatever settings we want, so as a test I used a bitrate of 380 Kbit - and it worked totally fine without any issues. The only thing that I question is that if Apple says that it only works at 160 Kbit, what can go wrong if we use a higher rate, i.e. will it work in some situations, but not in others?

Simon "Smash" Ashby

Kurt wrote:Maybe it's only guaranteed for smooth playback up to the standard setting on all iDevices? For example, maybe an iPhone 4S doesn't have the processing power to play back a higher specced file?

Interesting point.

The official specs for the 4s are exactly the official specs for the 5.

The maximum (listed) video bitrates are as follows,

iPhone 4s/5: 62.5 Mbit
iPhone 4: 14 Mbit
iPhone Original/3G/3GS: 1.5 Mbit

However, the maximum "official" audio bitrate is 160 Kbit for all models of iPhone.

So, where 160 Kbit was probably an appropriate bitrate for audio, when video is limited to 1.5 Mbit SD (as it was with the first 3 Generations of the iPhone, the audio bitrate has not "officially" changed, but the video bitrate has increased by 4160%

If the audio bitrate had increased at the same level, the audio bitrate on the iPhone 5 would actually be 6.6 Mbit...
or to put it another way... 7.1 Channel 24/96 1DTS HD (Not "Master Audio" though) coming out of our iPhones.

I just think it's not ideal that audio hasn't been upgraded, but video quality has been increased so massively.

Simon "Smash" Ashby

Seems all the RnD money is going into moving high quality images around. That's where the new money is.
Wanting good quality audio is old school.

One (small) consolation is the iphone 5 earbuds are the best earbuds I've ever heard.
The bottom end is astonishing for a pair of little things.

The Tasmanian wrote:One (small) consolation is the iphone 5 earbuds are the best earbuds I've ever heard.
The bottom end is astonishing for a pair of little things.

I've seen the actual measured specs, and the D/A's are actually pretty impressive too.
Like seriously impressive.

In other news, we have discovered that if we use the Apple H.264 settings, if the audio is above 160Kb/s it will not load onto the iPhone, however, if we use another encoder, like our Matrox Max cards, it loads onto the iPhone and plays perfectly. It's almost like the Apple encoder is flagging the file as out of spec...

Simon "Smash" Ashby.