View Source Membrane.H264.FFmpeg.Encoder (Membrane H264 FFmpeg plugin v0.26.1)
Membrane element that encodes raw video frames to H264 format.
The element expects each frame to be received in a separate buffer, so the parser
(Membrane.Element.RawVideo.Parser
) may be required in a pipeline before
the encoder (e.g. when input is read from Membrane.File.Source
).
Additionally, the encoder has to receive proper stream_format with picture format and dimensions before any encoding takes place.
Please check t/0
for available options.
element-options
Element options
Passed via struct Membrane.H264.FFmpeg.Encoder.t/0
crf
0..63
Default value:
23
Constant rate factor that affects the quality of output stream. Value of 0 is lossless compression while 51 (for 8-bit samples) or 63 (10-bit) offers the worst quality. The range is exponential, so increasing the CRF value +6 results in roughly half the bitrate / file size, while -6 leads to roughly twice the bitrate.preset
preset()
Default value:
:medium
Collection of predefined options providing certain encoding. The slower the preset chosen, the higher compression for the same quality can be achieved.profile
H264.profile_t() | nil
Default value:
nil
Sets a limit on the features that the encoder will use to the ones supported in a provided H264 profile. Said features will have to be supported by the decoder in order to decode the resulting video. It may override other, more specific options affecting compression (e.g settingmax_b_frames
to 2 while profile is set to:baseline
will have no effect and no B-frames will be present).use_shm?
boolean()
Default value:
false
max_b_frames
non_neg_integer() | nil
Default value:
nil
Maximum number of B-frames between non-B-frames. Set to 0 to encode video without b-framesgop_size
non_neg_integer() | nil
Default value:
nil
Number of frames in a group of pictures.
pads
Pads
input
:input
Accepted formats:
%RawVideo{pixel_format: format, aligned: true} when format in [:I420, :I422]
Direction: | :input |
Availability: | :always |
Mode: | :pull |
Demand mode: | :auto |
Demand unit: | :buffers |
output
:output
Accepted formats:
%H264{alignment: :au}
Direction: | :output |
Availability: | :always |
Mode: | :pull |
Demand mode: | :auto |
Link to this section Summary
Link to this section Types
@type preset() ::
:ultrafast
| :superfast
| :veryfast
| :faster
| :fast
| :medium
| :slow
| :slower
| :veryslow
| :placebo
@type t() :: %Membrane.H264.FFmpeg.Encoder{ crf: 0..63, gop_size: non_neg_integer() | nil, max_b_frames: non_neg_integer() | nil, preset: preset(), profile: Membrane.H264.profile_t() | nil, use_shm?: boolean() }
Struct containing options for Membrane.H264.FFmpeg.Encoder
Link to this section Functions
@spec options() :: keyword()
Returns description of options available for this module