Scrcpy: poor performance (high lag & low frame-rate) on cheap MediaTek budget phone

[Osndok]

Greetings.

I just tried scrcpy for the first time, and I really like the concept.

One thing that confuses me, however, is the many references to great performance, and lack of negative reports here on github, when my first & only convenient experience with it seemed to suffer greatly.

Is there anything I can do to help find, diagnose, or workaround this bottleneck?

Details:

• Phone: BLU Studio X
• CPU: MT6737
• connected via USB 2.0 / 480Mbps
• linux fedora 28
• "very capable" pc hardware

Observations:

• ~simply launching scrcpy seems to interfere with my linux gui (window shadows become black boxes), but it is returned to normal once scrcpy exits~
• there is a significant time-lag between when an image is displayed on the android screen, and it appears on the computer (I estimate at approx. 2 seconds)
• there is a very low frame rate (I estimate somewhere in the 5-to-10 fps range)
• If I just look at the Android screen, the input lag is nearly zero... silky-smooth!
• the CPU usage on the android device seems to be quite low! (~3%)

What I have tried:

• using the bandwidth limiter - results in poor image quality, but the same lag & frame-rate
• mucking with the target frame & i-frame rates in the ScreenEncoder
• setting MediaFormat.KEY_PRIORITY to 0 (real-time)
• re-arranging the encoding loop to re-use the codec, rather than rebuilding it

Next I'll try a "real" phone :-) ... whenever I find the time.

Thanks for making this! & making it open-source!

[Osndok]

Almost forgot! This was the only interesting logcat statement I could find (repeated, but not incessantly):

07-23 14:32:18.859  1760 19397 E GraphicBufferSource: mLatestBufferUseCount is already 0.

There were also some debug messages about audio codec latency tokens, but they didn't seem super-interesting:

07-23 14:32:18.859  1760 19394 I VDO_LOG : [WRAPPER] ReleaseYUV
07-23 14:32:18.859  1760 19394 I VDO_LOG : [WRAPPER] UpdateBitstreamWP
07-23 14:32:18.859  1760 19394 I VDO_LOG : Encode size 175
07-23 14:32:18.859  1760 19394 D MtkOmxVenc: [0xb0e72800] AVC EncTime=84, RGB_2_YUV=0, buf timestamp=303242289 (303242289910) IsKey(0), Size(175) : in VA=0xAF81C460, offset=0x00000000, t=303242289910, len=12, flags=0x00000010 : out VA=0xA9D40000, offset=0x00000000
07-23 14:32:18.859  1760 19394 D MtkOmxVenc: [0xb0e72800] b0e72800 EBD (0xB5499460) (0xAF81C460), mNumPendingInput(0)
07-23 14:32:18.859  1760 19394 D MtkOmxVenc: [0xb0e72800] b0e72800 FBD (0xB5499280) (0xA9D40000) 303242289910 (175), mNumPendingOutput(7)
07-23 14:32:18.859  1760 19397 E GraphicBufferSource: mLatestBufferUseCount is already 0.
07-23 14:32:18.860 19377 19392 D ACodec  : give LatencyToken 541, 175
07-23 14:32:18.860 19377 19392 D ACodec  : [OMX.MTK.VIDEO.ENCODER.AVC] onOutputBufferDrained ID 13

[rom1v]

the CPU usage on the android device seems to be quite low! (~3%)

What about the CPU usage on the computer?

[Osndok]

There is no noticeable increase in cpu load while scrcpy is running (about 2% of one core).

[rom1v]

Does it work better if you record your device screen:

adb shell screenrecord /sdcard/file.mp4
adb pull /sdcard/file.mp4

?

[Osndok]

Yes. With that method, the frame rate is perfect.

One thing I notice, is a peculiar assortment of resolutions in the diagnostic output...

scrcpy startup:

• "INFO: Initial texture: 720x1280"

screenrecord startup:

• "The max width/height supported by codec is 640x480"

Playing the screenrecord output file:

• Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 368x640, 634 kb/s, SAR 1:1 DAR 23:40, 9.67 fps, 90k tbr, 90k tbn, 180k tbc (default)

[rom1v]

And with:

scrcpy -m640

?

[Osndok]

Wow! It's suddenly quite usable! How did I overlook that? Thanks!!!"

Is there anything more to be gained by this ticket, or should it be closed?

[rom1v]

OK, so your device hardware may not encode video fast enough above 640px. On "real" devices, it should work at 50~60 fps at 1920×1080.