Has anyone figured out why MKVs with VC-1 video streams seem to always be jumpy / stuttery??? All my AVC-encoded MKVs work beautifully, but the VC-1’s are just horrid.
If it’s encoded to the specs that the chip was built to decode, then the chip should play it fine… if it exceeds the chip’s designed capabilities, then the chip won’t have much success trying to play it back. That’s kinda what the specs are all about, and why they’re published.
But the other question is how are the files accessed? Does the bitrate exceed the transfer rate?
Where can I find these chip specs you mention?
The mkv I’m using has a vc-1 video stream that has a video bitrate of 19.4 mbps being served from a NAS via 1Gb ethernet. Does that exceed the chip’s specs?
MikeyC wrote:
Where can I find these chip specs you mention?
The manual?
VC-1 AP@L3 up to 1920x1080i30 (<60% of the B-picture macroblocks have 4 motion vectors), 1920x1080p24, or 1280x720p60 resolution. Up to 1920x1080i25, 1920x1080p24, or 1280x720p60 resolution if unconstrained 4MV bitstream.
The mkv I’m using has a vc-1 video stream that has a video bitrate of 19.4 mbps being served from a NAS via 1Gb ethernet. Does that exceed the chip’s specs?
Well, it depends what actual throughput the network has at each stage, and particularly whether wired/wireless.
Very few (if any) folks have reported being able to stream 1080p reliably over their wireless. On the other hand, I have no problems with 15mB/s on cruddy old 10/100. I’ve never tried higher bitrates networked – just local storage.
From manual-
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WMV9/VC-1 MP@HL up to 1280x720p60 (<90% of the P-picture macroblocks have 4 motioin vectors) or 1920x1080p24 resolution. Up to 1280x720p30 or 1920x1080i25 resolution if unconstrained 4MV bitstream.
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VC-1 AP@L3 up to 1920x1080i30 (<60% of the B-picture macroblocks have 4 motion vectors), 1920x1080p24, or 1280x720p60 resolution. Up to 1920x1080i25, 1920x1080p24, or 1280x720p60 resolution if unconstrained 4MV bitstream.
Thanks parnott… I thought I had both in the copy buffer.
RoofingGuy wrote:
VC-1 AP@L3 up to 1920x1080i30 (<60% of the B-picture macroblocks have 4 motion vectors), 1920x1080p24, or 1280x720p60 resolution. Up to 1920x1080i25, 1920x1080p24, or 1280x720p60 resolution if unconstrained 4MV bitstream.
Well, it depends what actual throughput the network has at each stage, and particularly whether wired/wireless.
Very few (if any) folks have reported being able to stream 1080p reliably over their wireless. On the other hand, I have no problems with 15mB/s on cruddy old 10/100. I’ve never tried higher bitrates networked – just local storage.
I’m not using wireles…it’s wired 1GB Ethernet over Cat 6.
The video I’m trying to stream is within those specs:
Here’s the media info
Video
ID : 1
Format : VC-1
Format profile : AP@L3
Codec ID : WVC1
Codec ID/Hint : Microsoft
Duration : 2h 2mn
Bit rate : 19.4 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.391
Stream size : 16.6 GiB (91%)
Audio
ID : 2
Format : DTS
Format/Info : Digital Theater Systems
Codec ID : A_DTS
Duration : 2h 2mn
Bit rate mode : Constant
Bit rate : 1 510 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Compression mode : Lossy
Stream size : 1.29 GiB (7%)
Language : English
Text #1
ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Language : English
Now that you have no problem with AVC encoded MKV, why not transcode VC-1 to AVC?
MikeyC wrote:
The video I’m trying to stream is within those specs
Well, unfortunately the MediaInfo isn’t very helpful in this case… it doesn’t really go into the macroblock details for the stream.
L3 is “allowed” a bitrate up to 45Mbit/s, but as the Sigma specs say, there are further constraints on that for the Sigma to decode an L3 stream. Without knowing what settings were actually used during the encoding, there’s no way to say whether the file is in spec or not.
RoofingGuy wrote:
Well, unfortunately the MediaInfo isn’t very helpful in this case… it doesn’t really go into the macroblock details for the stream.
L3 is “allowed” a bitrate up to 45Mbit/s, but as the Sigma specs say, there are further constraints on that for the Sigma to decode an L3 stream. Without knowing what settings were actually used during the encoding, there’s no way to say whether the file is in spec or not.
How can I find these details out? Where can I find those Sigma specs?
