#11352: On the state of FFmpeg's ffv1_vulkan encoder implementation on Intel &
NVIDIA
-------------------------------------+-------------------------------------
Reporter: Dennis E. | Type: defect
Mungai |
Status: new | Priority: normal
Component: avcodec | Version: git-
Keywords: vulkan ffv1 | master
ffv1_vulkan | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
The subject matter above refers.
Sample command-lines are provided for reference, see the notes section
below.
**(a). Intel:**
{{{
ffmpeg \
-init_hw_device vulkan=vk:0 \
-hwaccel vulkan -hwaccel_output_format vulkan \
-hwaccel_device vk -filter_hw_device vk \
-loglevel info \
-fflags +genpts \
-i '4KIOS.mov' \
-vf "bwdif_vulkan,libplacebo=format=yuv420p" \
-c:v ffv1_vulkan \
-r:v 60 -g:v 2 -level:v 4 -strict -2 -coder:v 2 -context:v 1 \
-c:a libfdk_aac -b:a 128k -ar 48000 -ac 2 \
-map "0:v" -map "0:a" \
-max_muxing_queue_size 8192 -max_interleave_delta 0 \
-flags -global_header+cgop \
-y -f matroska "ticketx_ffv1.mkv"
}}}
**(b). NVIDIA:**
{{{
ffmpeg \
-init_hw_device vulkan=vk:0 \
-hwaccel vulkan -hwaccel_output_format vulkan \
-hwaccel_device vk -filter_hw_device vk \
-loglevel info \
-fflags +genpts \
-i '4KIOS.mov' \
-vf "bwdif_vulkan,libplacebo=format=yuv420p" \
-c:v ffv1_vulkan \
-r:v 60 -g:v 2 -level:v 4 -strict -2 -coder:v 2 -context:v 1 \
-c:a libfdk_aac -b:a 128k -ar 48000 -ac 2 \
-map "0:v" -map "0:a" \
-max_delay 5000000 -max_muxing_queue_size 8192 -max_interleave_delta 0 \
-flags -global_header+cgop \
-y -f matroska "ticket4_ffv1.mkv"
}}}
**Runtime notes:**
It's observed that the encoder also works quite well with and without
using Vulkan H/W Accelerated decode, producing consistent results across
multiple runs per test platform with and without Vulkan H/W Accelerated
decode.
As noted by Lynne on IRC regarding this encoder, handling yuv420p requires
the following conditions to be met:
i. Either 64 pixel aligned images for both h and v.
ii. And using version 4 (Pass `-level 4 -strict -2`).
The example commands above have the flags `-strict -2` and `-level:v 4`
set to match the constraints defined above.
**Oddities/bugs:**
1. Even with identical parameters, the file sizes produced by Intel's and
NVIDIA's `ffv1_vulkan` instances differ significantly.
Intel's anv driver produces ridiculously massive files as shown below:
The file from NVIDIA's session,named "ticket4_ffv1.mkv" is about 4.9G in
size.
Intel's session output with the same settings, named "ticketx_ffv1.mkv",
weighs at 41 GB.
2. NVIDIA's performance with this encoder, as tested on the RTX 4060 Max Q
with a 4k input sample is at about ~0.63x speed.
Intel's performance on the Integrated Raptor Lake GPU with the ANV driver
clocks in at a paltry speed of 0.0907x. 7x slower.
3. With NVIDIA, the {{{ffv1_vulkan encoder}}} will hang at a sporadic
frame on each session *if* `-g:v` is higher than 2, regardless of the
`-level:v` setting, all else being constant.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11352>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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