x264enc
This element encodes raw video into H264 compressed data, also otherwise known as MPEG-4 AVC (Advanced Video Codec).
The pass property controls the type of encoding. In case of Constant Bitrate Encoding (actually ABR), the bitrate will determine the quality of the encoding. This will similarly be the case if this target bitrate is to obtained in multiple (2 or 3) pass encoding. Alternatively, one may choose to perform Constant Quantizer or Quality encoding, in which case the quantizer property controls much of the outcome, in that case bitrate is the maximum bitrate.
The H264 profile that is eventually used depends on a few settings. If dct8x8 is enabled, then High profile is used. Otherwise, if cabac entropy coding is enabled or bframes are allowed, then Main Profile is in effect, and otherwise Baseline profile applies. The high profile is imposed by default, which is fine for most software players and settings, but in some cases (e.g. hardware platforms) a more restricted profile/level may be necessary. The recommended way to set a profile is to set it in the downstream caps.
If a preset/tuning are specified then these will define the default values and the property defaults will be ignored. After this the option-string property is applied, followed by the user-set properties, fast first pass restrictions and finally the profile restrictions.
Some settings, including the default settings, may lead to quite some latency (i.e. frame buffering) in the encoder. This may cause problems with pipeline stalling in non-trivial pipelines, because the encoder latency is often considerably higher than the default size of a simple queue element. Such problems are caused by one of the queues in the other non-x264enc streams/branches filling up and blocking upstream. They can be fixed by relaxing the default time/size/buffer limits on the queue elements in the non-x264 branches, or using a (single) multiqueue element for all branches. Also see the last example below. You can also work around this problem by setting the tune=zerolatency property, but this will affect overall encoding quality so may not be appropriate for your use case.
Example pipeline
gst-launch-1.0 -v videotestsrc num-buffers=1000 ! x264enc qp-min=18 ! \
avimux ! filesink location=videotestsrc.avi
This example pipeline will encode a test video source to H264 muxed in an AVI container, while ensuring a sane minimum quantization factor to avoid some (excessive) waste. You should ideally never put H264 into an AVI container (or really anything else, for that matter) - use Matroska or MP4/QuickTime or MPEG-TS instead.
gst-launch-1.0 -v videotestsrc num-buffers=1000 ! x264enc pass=quant ! \
matroskamux ! filesink location=videotestsrc.mkv
This example pipeline will encode a test video source to H264 using fixed quantization, and muxes it in a Matroska container.
gst-launch-1.0 -v videotestsrc num-buffers=1000 ! x264enc pass=5 quantizer=25 speed-preset=6 ! video/x-h264, profile=baseline ! \
qtmux ! filesink location=videotestsrc.mov
This example pipeline will encode a test video source to H264 using constant quality at around Q25 using the 'medium' speed/quality preset and restricting the options used so that the output is H.264 Baseline Profile compliant and finally multiplexing the output in Quicktime mov format.
gst-launch-1.0 -v videotestsrc num-buffers=1000 ! tee name=t ! queue ! videoconvert ! autovideosink \
t. ! queue ! x264enc rc-lookahead=5 ! fakesink
This example pipeline will encode a test video source to H.264 while displaying the input material at the same time. As mentioned above, specific settings are needed in this case to avoid pipeline stalling. Depending on goals and context, other approaches are possible, e.g. tune=zerolatency might be configured, or queue sizes increased.
Hierarchy
GObject ╰──GInitiallyUnowned ╰──GstObject ╰──GstElement ╰──GstVideoEncoder ╰──x264enc
Implemented interfaces
Factory details
Authors: – Josef Zlomek
Classification: – Codec/Encoder/Video
Rank – primary
Plugin – x264
Package – GStreamer Ugly Plug-ins
Pad Templates
sink
video/x-raw:
framerate: [ 0/1, 2147483647/1 ]
width: [ 1, 2147483647 ]
height: [ 1, 2147483647 ]
format: { Y444, Y42B, I420, YV12, NV12, GRAY8, Y444_10LE, I422_10LE, I420_10LE }
src
video/x-h264:
framerate: [ 0/1, 2147483647/1 ]
width: [ 1, 2147483647 ]
height: [ 1, 2147483647 ]
stream-format: { (string)avc, (string)byte-stream }
alignment: au
profile: { (string)high-4:4:4, (string)high-4:2:2, (string)high-10, (string)high, (string)main, (string)baseline, (string)constrained-baseline, (string)high-4:4:4-intra, (string)high-4:2:2-intra, (string)high-10-intra }
Properties
analyse
“analyse” GstX264EncAnalyse *
Partitions to consider
Flags : Read / Write
Default value : (none)
b-adapt
“b-adapt” gboolean
Automatically decide how many B-frames to use
Flags : Read / Write
Default value : true
b-pyramid
“b-pyramid” gboolean
Keep some B-frames as references
Flags : Read / Write
Default value : false
byte-stream
“byte-stream” gboolean
Generate byte stream format of NALU
Flags : Read / Write
Default value : false
frame-packing
“frame-packing” GstX264EncFramePacking *
Set frame packing mode for Stereoscopic content
Flags : Read / Write
Default value : auto (-1)
intra-refresh
“intra-refresh” gboolean
Use Periodic Intra Refresh instead of IDR frames
Flags : Read / Write
Default value : false
ip-factor
“ip-factor” gfloat
Quantizer factor between I- and P-frames
Flags : Read / Write
Default value : 1.4
key-int-max
“key-int-max” guint
Maximal distance between two key-frames (0 for automatic)
Flags : Read / Write
Default value : 0
me
“me” GstX264EncMe *
Integer pixel motion estimation method
Flags : Read / Write
Default value : hex (1)
multipass-cache-file
“multipass-cache-file” gchararray
Filename for multipass cache file
Flags : Read / Write
Default value : x264.log
nal-hrd
“nal-hrd” GstX264EncNalHrd *
Signal Hypothetical Reference Decoder information.
Required for Blu-ray streams, television broadcast and a few other specialist areas.
It can be used for instance to force true CBR, and will cause the encoder to output NULL padding packets.
Flags : Read / Write
Default value : none (0)
Since : 1.26
noise-reduction
“noise-reduction” guint
Noise reduction strength
Flags : Read / Write
Default value : 0
option-string
“option-string” gchararray
String of x264 options (overridden by element properties) in the format "key1=value1:key2=value2".
Flags : Read / Write
pb-factor
“pb-factor” gfloat
Quantizer factor between P- and B-frames
Flags : Read / Write
Default value : 1.3
psy-tune
“psy-tune” GstX264EncPsyTune *
Preset name for psychovisual tuning options
Flags : Read / Write
Default value : none (0)
qp-step
“qp-step” guint
Maximum quantizer difference between frames
Flags : Read / Write
Default value : 4
quantizer
“quantizer” guint
Constant quantizer or quality to apply
Flags : Read / Write
Default value : 21
rc-lookahead
“rc-lookahead” gint
Number of frames for frametype lookahead
Flags : Read / Write
Default value : 40
sliced-threads
“sliced-threads” gboolean
Low latency but lower efficiency threading
Flags : Read / Write
Default value : false
speed-preset
“speed-preset” GstX264EncPreset *
Preset name for speed/quality tradeoff options (can affect decode compatibility - impose restrictions separately for your target decoder)
Flags : Read / Write
Default value : medium (6)
subme
“subme” guint
Subpixel motion estimation and partition decision quality: 1=fast, 10=best
Flags : Read / Write
Default value : 1
sync-lookahead
“sync-lookahead” gint
Number of buffer frames for threaded lookahead (-1 for automatic)
Flags : Read / Write
Default value : -1
threads
“threads” guint
Number of threads used by the codec (0 for automatic)
Flags : Read / Write
Default value : 0
trellis
“trellis” gboolean
Enable trellis searched quantization
Flags : Read / Write
Default value : true
tune
“tune” GstX264EncTune *
Preset name for non-psychovisual tuning options
Flags : Read / Write
Default value : (none)
vbv-buf-capacity
“vbv-buf-capacity” guint
Size of the VBV buffer in milliseconds
Flags : Read / Write
Default value : 600
weightb
“weightb” gboolean
Weighted prediction for B-frames
Flags : Read / Write
Default value : false
Named constants
GstX264EncAnalyse
Members
i4x4 (0x00000001) – i4x4
i8x8 (0x00000002) – i8x8
p8x8 (0x00000010) – p8x8
p4x4 (0x00000020) – p4x4
b8x8 (0x00000100) – b8x8
GstX264EncFramePacking
Members
auto (-1) – Automatic (use incoming video information)
checkerboard (0) – checkerboard - Left and Right pixels alternate in a checkerboard pattern
column-interleaved (1) – column interleaved - Alternating pixel columns represent Left and Right views
row-interleaved (2) – row interleaved - Alternating pixel rows represent Left and Right views
side-by-side (3) – side by side - The left half of the frame contains the Left eye view, the right half the Right eye view
top-bottom (4) – top bottom - L is on top, R on bottom
frame-interleaved (5) – frame interleaved - Each frame contains either Left or Right view alternately
GstX264EncMe
Members
dia (0) – dia
hex (1) – hex
umh (2) – umh
esa (3) – esa
tesa (4) – tesa
GstX264EncNalHrd
Signal HRD information. Required for Blu-ray streams, television broadcast and a few other specialist areas.
Members
none (0) – None
vbr (1) – Variable bitrate
cbr (2) – Constant bitrate
Since : 1.26
GstX264EncPass
Members
cbr (0) – Constant Bitrate Encoding
quant (4) – Constant Quantizer
qual (5) – Constant Quality
pass1 (17) – VBR Encoding - Pass 1
pass2 (18) – VBR Encoding - Pass 2
pass3 (19) – VBR Encoding - Pass 3
GstX264EncPreset
Members
None (0) – No preset
ultrafast (1) – ultrafast
superfast (2) – superfast
veryfast (3) – veryfast
faster (4) – faster
fast (5) – fast
medium (6) – medium
slow (7) – slow
slower (8) – slower
veryslow (9) – veryslow
placebo (10) – placebo
GstX264EncPsyTune
Members
none (0) – No tuning
film (1) – Film
animation (2) – Animation
grain (3) – Grain
psnr (4) – PSNR
ssim (5) – SSIM
GstX264EncTune
Members
stillimage (0x00000001) – Still image
fastdecode (0x00000002) – Fast decode
zerolatency (0x00000004) – Zero latency
The results of the search are