Adapter

class Adapter(**properties: Any)

Superclasses: Object

Constructors:

Adapter(**properties)
new() -> GstBase.Adapter

Constructors

class Adapter
classmethod new() → Adapter

Creates a new Adapter. Free with unref().

Methods

class Adapter
available() → int

Gets the maximum amount of bytes available, that is it returns the maximum value that can be supplied to map() without that function returning None.

available_fast() → int

Gets the maximum number of bytes that are immediately available without requiring any expensive operations (like copying the data into a temporary buffer).

clear() → None

Removes all buffers from adapter.

distance_from_discont() → int

Get the distance in bytes since the last buffer with the %GST_BUFFER_FLAG_DISCONT flag.

The distance will be reset to 0 for all buffers with %GST_BUFFER_FLAG_DISCONT on them, and then calculated for all other following buffers based on their size.

Added in version 1.10.

dts_at_discont() → int

Get the DTS that was on the last buffer with the GST_BUFFER_FLAG_DISCONT flag, or GST_CLOCK_TIME_NONE.

Added in version 1.10.

flush(flush: int) → None

Flushes the first flush bytes in the adapter. The caller must ensure that at least this many bytes are available.

See also: map(), unmap()

Parameters:

flush – the number of bytes to flush

get_buffer(nbytes: int) → Buffer | None

Returns a Buffer containing the first nbytes of the adapter, but does not flush them from the adapter. See take_buffer() for details.

Caller owns a reference to the returned buffer. gst_buffer_unref() after usage.

Free-function: gst_buffer_unref

Added in version 1.6.

Parameters:

nbytes – the number of bytes to get

get_buffer_fast(nbytes: int) → Buffer | None

Returns a Buffer containing the first nbytes of the adapter, but does not flush them from the adapter. See take_buffer_fast() for details.

Caller owns a reference to the returned buffer. gst_buffer_unref() after usage.

Free-function: gst_buffer_unref

Added in version 1.6.

Parameters:

nbytes – the number of bytes to get

get_buffer_list(nbytes: int) → BufferList | None

Returns a BufferList of buffers containing the first nbytes bytes of the adapter but does not flush them from the adapter. See take_buffer_list() for details.

Caller owns the returned list. Call gst_buffer_list_unref() to free the list after usage.

Added in version 1.6.

Parameters:

nbytes – the number of bytes to get

get_list(nbytes: int) → list[Buffer] | None

Returns a GList of buffers containing the first nbytes bytes of the adapter, but does not flush them from the adapter. See take_list() for details.

Caller owns returned list and contained buffers. gst_buffer_unref() each buffer in the list before freeing the list after usage.

Added in version 1.6.

Parameters:

nbytes – the number of bytes to get

map() → bytes | None

Gets the first size bytes stored in the adapter. The returned pointer is valid until the next function is called on the adapter.

Note that setting the returned pointer as the data of a Buffer is incorrect for general-purpose plugins. The reason is that if a downstream element stores the buffer so that it has access to it outside of the bounds of its chain function, the buffer will have an invalid data pointer after your element flushes the bytes. In that case you should use take(), which returns a freshly-allocated buffer that you can set as Buffer memory or the potentially more performant take_buffer().

Returns None if size bytes are not available.

masked_scan_uint32(mask: int, pattern: int, offset: int, size: int) → int

Scan for pattern pattern with applied mask mask in the adapter data, starting from offset offset.

The bytes in pattern and mask are interpreted left-to-right, regardless of endianness. All four bytes of the pattern must be present in the adapter for it to match, even if the first or last bytes are masked out.

It is an error to call this function without making sure that there is enough data (offset+size bytes) in the adapter.

This function calls masked_scan_uint32_peek() passing None for value.

Parameters:

  • mask – mask to apply to data before matching against pattern

  • pattern – pattern to match (after mask is applied)

  • offset – offset into the adapter data from which to start scanning, returns the last scanned position.

  • size – number of bytes to scan from offset

masked_scan_uint32_peek(mask: int, pattern: int, offset: int, size: int) → tuple[int, int]

Scan for pattern pattern with applied mask mask in the adapter data, starting from offset offset. If a match is found, the value that matched is returned through value, otherwise value is left untouched.

The bytes in pattern and mask are interpreted left-to-right, regardless of endianness. All four bytes of the pattern must be present in the adapter for it to match, even if the first or last bytes are masked out.

It is an error to call this function without making sure that there is enough data (offset+size bytes) in the adapter.

Parameters:

  • mask – mask to apply to data before matching against pattern

  • pattern – pattern to match (after mask is applied)

  • offset – offset into the adapter data from which to start scanning, returns the last scanned position.

  • size – number of bytes to scan from offset

offset_at_discont() → int

Get the offset that was on the last buffer with the GST_BUFFER_FLAG_DISCONT flag, or GST_BUFFER_OFFSET_NONE.

Added in version 1.10.

prev_dts() → tuple[int, int]

Get the dts that was before the current byte in the adapter. When distance is given, the amount of bytes between the dts and the current position is returned.

The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when the adapter is first created or when it is cleared. This also means that before the first byte with a dts is removed from the adapter, the dts and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.

prev_dts_at_offset(offset: int) → tuple[int, int]

Get the dts that was before the byte at offset offset in the adapter. When distance is given, the amount of bytes between the dts and the current position is returned.

The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when the adapter is first created or when it is cleared. This also means that before the first byte with a dts is removed from the adapter, the dts and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.

Added in version 1.2.

Parameters:

offset – the offset in the adapter at which to get timestamp

prev_offset() → tuple[int, int]

Get the offset that was before the current byte in the adapter. When distance is given, the amount of bytes between the offset and the current position is returned.

The offset is reset to GST_BUFFER_OFFSET_NONE and the distance is set to 0 when the adapter is first created or when it is cleared. This also means that before the first byte with an offset is removed from the adapter, the offset and distance returned are GST_BUFFER_OFFSET_NONE and 0 respectively.

Added in version 1.10.

prev_pts() → tuple[int, int]

Get the pts that was before the current byte in the adapter. When distance is given, the amount of bytes between the pts and the current position is returned.

The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when the adapter is first created or when it is cleared. This also means that before the first byte with a pts is removed from the adapter, the pts and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.

prev_pts_at_offset(offset: int) → tuple[int, int]

Get the pts that was before the byte at offset offset in the adapter. When distance is given, the amount of bytes between the pts and the current position is returned.

The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when the adapter is first created or when it is cleared. This also means that before the first byte with a pts is removed from the adapter, the pts and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.

Added in version 1.2.

Parameters:

offset – the offset in the adapter at which to get timestamp

pts_at_discont() → int

Get the PTS that was on the last buffer with the GST_BUFFER_FLAG_DISCONT flag, or GST_CLOCK_TIME_NONE.

Added in version 1.10.

push(buf: Buffer) → None

Adds the data from buf to the data stored inside adapter and takes ownership of the buffer.

Parameters:

buf – a Buffer to add to queue in the adapter

take() → bytes | None

Returns a freshly allocated buffer containing the first nbytes bytes of the adapter. The returned bytes will be flushed from the adapter.

Caller owns returned value. g_free after usage.

Free-function: g_free

take_buffer(nbytes: int) → Buffer | None

Returns a Buffer containing the first nbytes bytes of the adapter. The returned bytes will be flushed from the adapter. This function is potentially more performant than take() since it can reuse the memory in pushed buffers by subbuffering or merging. This function will always return a buffer with a single memory region.

Note that no assumptions should be made as to whether certain buffer flags such as the DISCONT flag are set on the returned buffer, or not. The caller needs to explicitly set or unset flags that should be set or unset.

Since 1.6 this will also copy over all GstMeta of the input buffers except for meta with the %GST_META_FLAG_POOLED flag or with the “memory” tag.

Caller owns a reference to the returned buffer. gst_buffer_unref() after usage.

Free-function: gst_buffer_unref

Parameters:

nbytes – the number of bytes to take

take_buffer_fast(nbytes: int) → Buffer | None

Returns a Buffer containing the first nbytes of the adapter. The returned bytes will be flushed from the adapter. This function is potentially more performant than take_buffer() since it can reuse the memory in pushed buffers by subbuffering or merging. Unlike take_buffer(), the returned buffer may be composed of multiple non-contiguous Memory objects, no copies are made.

Note that no assumptions should be made as to whether certain buffer flags such as the DISCONT flag are set on the returned buffer, or not. The caller needs to explicitly set or unset flags that should be set or unset.

This will also copy over all GstMeta of the input buffers except for meta with the %GST_META_FLAG_POOLED flag or with the “memory” tag.

This function can return buffer up to the return value of available() without making copies if possible.

Caller owns a reference to the returned buffer. gst_buffer_unref() after usage.

Free-function: gst_buffer_unref

Added in version 1.2.

Parameters:

nbytes – the number of bytes to take

take_buffer_list(nbytes: int) → BufferList | None

Returns a BufferList of buffers containing the first nbytes bytes of the adapter. The returned bytes will be flushed from the adapter. When the caller can deal with individual buffers, this function is more performant because no memory should be copied.

Caller owns the returned list. Call gst_buffer_list_unref() to free the list after usage.

Added in version 1.6.

Parameters:

nbytes – the number of bytes to take

take_list(nbytes: int) → list[Buffer] | None

Returns a GList of buffers containing the first nbytes bytes of the adapter. The returned bytes will be flushed from the adapter. When the caller can deal with individual buffers, this function is more performant because no memory should be copied.

Caller owns returned list and contained buffers. gst_buffer_unref() each buffer in the list before freeing the list after usage.

Parameters:

nbytes – the number of bytes to take

unmap() → None

Releases the memory obtained with the last map().