daalaenc.h - Man Page

#define _daala_daalaenc_H   (1)

OD_SET_RATE_FLAGS flags
These are the flags available for use with OD_SET_RATE_FLAGS.

#define OD_RATECTL_DROP_FRAMES   (0x1)
Drop frames to keep within bitrate buffer constraints.
#define OD_RATECTL_CAP_OVERFLOW   (0x2)
Ignore bitrate buffer overflows.
#define OD_RATECTL_CAP_UNDERFLOW   (0x4)
Ignore bitrate buffer underflows.

Encoder state
The following data structure is opaque, and its contents are not publicly defined by this API.

Referring to its internals directly is unsupported, and may break without warning.

typedef struct daala_enc_ctx daala_enc_ctx
The encoder context.

You must link to libdaalabase and libdaalaenc if you use any of the functions in this section.

The functions are listed in the order they are used in a typical encode. The basic steps are:

·

Fill in a daala_info structure with details on the format of the video you wish to encode.

·

Allocate a daala_enc_ctx handle with daala_encode_alloc().

·

Perform any additional encoder configuration required with daala_encode_ctl().

·

Repeatedly call daala_encode_flusheader() to retrieve all the header packets.

·

For each uncompressed frame:

 ·

Submit the compressed frame via daala_encode_img_in().

 ·

Repeatedly call daala_encode_packet_out() to retrieve any video data packets that are ready.

·

Call daala_comment_clear() to release all comments allocated.

·

Call daala_encode_free() to release all encoder memory.

#define OD_SET_QUANT   4000
Set the quantizer scale.
#define OD_SET_COMPLEXITY   4002
Configure the encoder's computational complexity level.
#define OD_GET_COMPLEXITY   4004
Get the encoder's computational complexity level.
#define OD_SET_ACTIVITY_MASKING   4006
Whether activity masking should be used or not.
#define OD_SET_QM   4008
Which quantization matrix to use.
#define OD_SET_DERING   4010
Whether the bilinear postprocessing filter should be used or not.
#define OD_SET_MC_CHROMA   4100
Whether the motion compensation search should use the chroma planes in addition to the luma plane.
#define OD_SET_MV_RES_MIN   4102
Minimum motion vectors resolution for the motion compensation search.
#define OD_SET_MV_LEVEL_MIN   4104
Minimum motion vectors level for the motion compensation search.
#define OD_SET_MV_LEVEL_MAX   4106
Maximum motion vectors level for the motion compensation search.
#define OD_SET_MC_SATD   4108
Whether the SATD metric should be used in motion compensation or not.
#define OD_SET_B_FRAMES   4110
Number of B frames used by encoder.
#define OD_SET_BITRATE   4112
Sets the current encoding bitrate.
#define OD_SET_RATE_FLAGS   4114
Modifies the default bitrate management behavior.
#define OD_SET_RATE_BUFFER   4116
Sets the size of the bitrate management bit reservoir as a function of number of frames.
#define OD_2PASS_OUT   4118
Enable pass 1 of two-pass encoding mode and retrieve the first pass metrics.
#define OD_2PASS_IN   4120
Submits two-pass encoding metric data collected the first encoding pass to the second pass.
daala_enc_ctx * daala_encode_create (const daala_info *info)
Allocates and initializes an encoder instance.
int daala_encode_ctl (daala_enc_ctx *enc, int req, void *buf, size_t buf_sz)
Encoder control function.
int daala_encode_flush_header (daala_enc_ctx *enc, daala_comment *comments, daala_packet *dp)
Outputs the next header packet.
int daala_encode_img_in (daala_enc_ctx *enc, daala_image *img, int duration)
Submits an uncompressed frame to the encoder.
int daala_encode_packet_out (daala_enc_ctx *enc, int last, daala_packet *dp)
Retrieves encoded video data packets.
void daala_encode_free (daala_enc_ctx *enc)
Frees an allocated encoder instance.

Set the quantizer scale. The passed buffer is interpreted as containing a single int. The valid range is 0-511.

Configure the encoder's computational complexity level.

See also

OD_GET_COMPLEXITY

Parameters

Get the encoder's computational complexity level.

See also

OD_SET_COMPLEXITY

Parameters

Whether activity masking should be used or not.

Parameters

Which quantization matrix to use.

Parameters

Whether the bilinear postprocessing filter should be used or not.

Parameters

Whether the motion compensation search should use the chroma planes in addition to the luma plane.

Parameters

Minimum motion vectors resolution for the motion compensation search.

Parameters

Minimum motion vectors level for the motion compensation search. If this level is greater than the maximum level, the maximum level will be used instead.

Parameters

Maximum motion vectors level for the motion compensation search.

Parameters

Whether the SATD metric should be used in motion compensation or not.

Parameters

Number of B frames used by encoder.

Parameters

Sets the current encoding bitrate. Once a bitrate is set, the encoder must use a rate-controlled mode for all future frames (this restriction may be relaxed in a future version). Due to the buffer delay, the exact bitrate of each section of the encode is not guaranteed. The encoder may have already used more bits than allowed for the frames it has encoded, expecting to make them up in future frames, or it may have used fewer, holding the excess in reserve. The exact transition between two bitrates is not well-defined by this API, but may be affected by flags set with OD_SET_RATE_FLAGS. After a number of frames equal to the buffer delay, one may expect further output to average at the target bitrate.

Parameters

buf long: The new target bitrate, in bits per second.

Return values

OD_SUCCESS Success.
OD_EFAULT enc or buf is NULL.
OD_EINVAL The target bitrate was not positive. A future version of this library may allow passing 0 to disabled rate-controlled mode and return to a quality-based mode, in which case this function will not return an error for that value.
OD_EIMPL Not supported by this implementation.

Modifies the default bitrate management behavior. Use to allow or disallow frame dropping, and to enable or disable capping bit reservoir overflows and underflows. See the list of available flags. The flags are set by default to OD_RATECTL_DROP_FRAMES|OD_RATECTL_CAP_OVERFLOW.

Parameters

buf int: Any combination of the available flags:

• OD_RATECTL_DROP_FRAMES: Enable frame dropping.
• OD_RATECTL_CAP_OVERFLOW: Don't bank excess bits for later use.
• OD_RATECTL_CAP_UNDERFLOW: Don't try to make up shortfalls later.

Return values

OD_SUCCESS Success.
OD_EFAULT enc or buf is NULL.
OD_EINVAL buf_sz is not sizeof(int) or rate control is not enabled.
OD_EIMPL Not supported by this implementation in the current encoding mode.

Sets the size of the bitrate management bit reservoir as a function of number of frames. The reservoir size affects how quickly bitrate management reacts to instantaneous changes in the video complexity. Larger reservoirs react more slowly, and provide better overall quality, but require more buffering by a client, adding more latency to live streams. By default, libdaala sets the reservoir to the maximum distance between keyframes, subject to a minimum and maximum limit. This call may be used to increase or decrease the reservoir, increasing or decreasing the allowed temporary variance in bitrate. An implementation may impose some limits on the size of a reservoir it can handle, in which case the actual reservoir size may not be exactly what was requested. The actual value set will be returned.

Parameters

buf int: Requested size of the reservoir measured in frames.
buf int: The actual size of the reservoir set.

Return values

OD_EFAULT enc or buf is NULL.
OD_EINVAL buf_sz is not sizeof(int), or rate control is not enabled. The buffer has an implementation defined minimum and maximum size and the value in buf will be adjusted to match the actual value set.
OD_EIMPL Not supported by this implementation in the current encoding mode.

Enable pass 1 of two-pass encoding mode and retrieve the first pass metrics. Pass 1 mode must be enabled before the first frame is encoded, and a target bitrate must have already been specified to the encoder. Although this does not have to be the exact rate that will be used in the second pass, closer values may produce better results. The first call returns the size of the two-pass header data, along with some placeholder content, and sets the encoder into pass 1 mode implicitly. This call sets the encoder to pass 1 mode implicitly. Then, a subsequent call must be made after each call to daala_encode_img_in() to retrieve the metrics for that frame. An additional, final call must be made to retrieve the summary data, containing such information as the total number of frames, etc. This must be stored in place of the placeholder data that was returned in the first call, before the frame metrics data. All of this data must be presented back to the encoder during pass 2 using OD_2PASS_IN.

Parameters

Return values

Submits two-pass encoding metric data collected the first encoding pass to the second pass. The first call must be made before the first frame is encoded, and a target bitrate must have already been specified to the encoder. It sets the encoder to pass 2 mode implicitly; this cannot be disabled. The encoder may require reading data from some or all of the frames in advance, depending on, e.g., the reservoir size used in the second pass. You must call this function repeatedly before each frame to provide data until either a) it fails to consume all of the data presented or b) all of the pass 1 data has been consumed. In the first case, you must save the remaining data to be presented after the next frame. You can call this function with a NULL argument to get an upper bound on the number of bytes that will be required before the next frame.

When pass 2 is first enabled, the default bit reservoir is set to the entire file; this gives maximum flexibility but can lead to very high peak rates. You can subsequently set it to another value with OD_SET_RATE_BUFFER (e.g., to set it to the keyframe interval for non-live streaming), however, you may then need to provide more data before the next frame.

Parameters

buf char[]: A buffer containing the data returned by OD_2PASS_OUT in pass 1. You may pass NULL for buf to return an upper bound on the number of additional bytes needed before the next frame. The summary data returned at the end of pass 1 must be at the head of the buffer on the first call with a non-NULL buf, and the placeholder data returned at the start of pass 1 should be omitted. After each call you should advance this buffer by the number of bytes consumed.

Return values

Drop frames to keep within bitrate buffer constraints. This can have a severe impact on quality, but is the only way to ensure that bitrate targets are met at low rates during sudden bursts of activity. It is enabled by default.

Ignore bitrate buffer overflows. If the encoder uses so few bits that the reservoir of available bits overflows, ignore the excess. The encoder will not try to use these extra bits in future frames. At high rates this may cause the result to be undersized, but allows a client to play the stream using a finite buffer; it should normally be enabled, which is the default.

Ignore bitrate buffer underflows. If the encoder uses so many bits that the reservoir of available bits underflows, ignore the deficit. The encoder will not try to make up these extra bits in future frames. At low rates this may cause the result to be oversized; it should normally be disabled, which is the default.

Allocates and initializes an encoder instance.

Parameters

info A daala_info struct filled with the desired encoding parameters.

Returns

The initialized daala_enc_ctx handle.

Return values

NULL if the encoding parameters were invalid.

Encoder control function. This is used to provide advanced control of the encoding process.

Parameters

enc A daala_enc_ctx handle.
req The control code to process. See the list of available control codes for details.
buf The parameters for this control code.
buf_sz The size of the parameter buffer.

Outputs the next header packet. This should be called repeatedly after encoder initialization until it return 0 to get all of the header packets, in order, before encoding actual video data.

Parameters

enc A daala_enc_ctx handle.
comments The metadata to place in the comment header, when it is encoded. Users should free the returned data with daala_comment_clear().
dp A daala_packet structure to fill. All of the elements of this structure will be set, including a pointer to the header data. The memory for the header data is owned by libdaala.

Returns

A positive value indicates that a header packet was successfully produced.

Return values

Submits an uncompressed frame to the encoder.

Parameters

enc A daala_enc_ctx handle.
img A buffer of image data to encode.
duration The duration to display the frame for, in timebase units. If a non-zero frame duration was specified in the header, then this parameter is ignored.

Return values

Retrieves encoded video data packets. This should be called repeatedly after each frame is submitted to flush any encoded packets, until it returns 0. The encoder will not buffer these packets as subsequent frames are compressed, so a failure to do so will result in lost video data.

Note

Current the encoder operates in a one-frame-in, one-packet-out manner. However, this may be changed in the future.

Parameters

enc A daala_enc_ctx handle. This ensures that a proper EOS flag is set on the last packet.
dp A daala_packet structure to fill. All of the elements of this structure will be set, including a pointer to the video data. The memory for the video data is owned by libdaala.

Returns

A positive value indicates that a video data packet was successfully produced.

Return values

Frees an allocated encoder instance.

Parameters

enc A daala_enc_ctx handle.