Query

Queries can be performed on pads (Pad.query) and elements (Element.query). Please note that some queries might need a running pipeline to work.

Queries can be created using the gst_query_new_*() functions. Query values can be set using gst_query_set_*(), and parsed using gst_query_parse_*() helpers.

The following example shows how to query the duration of a pipeline:

GstQuery *query;
gboolean res;
query = gst_query_new_duration (GST_FORMAT_TIME);
res = gst_element_query (pipeline, query);
if (res) {
gint64 duration;
gst_query_parse_duration (query, NULL, &amp;duration);
g_print ("duration = %"GST_TIME_FORMAT, GST_TIME_ARGS (duration));
} else {
g_print ("duration query failed...");
}
gst_query_unref (query);

class Query {

GstQuery* gstQuery;

protected

bool ownedRef;

GstQuery* getQueryStruct(bool transferOwnership);

void* getStruct();

this(GstQuery* gstQuery, bool ownedRef);

static Query newPosition(GstFormat format);

static Query newDuration(GstFormat format);

static Query newSeeking(GstFormat format);

static Query newFormats();

static Query newSegment(GstFormat format);

static Query newLatency();

static Query newUri();

static Query newScheduling();

static Query newDrain();

static Query newAcceptCaps(Caps caps);

static GType getType();

this(Caps caps, bool needPool);

this(GstFormat format);

this(Caps filter);

this(string contextType);

this(GstFormat srcFormat, long value, GstFormat destFormat);

this(GstQueryType type, Structure structure);

void addAllocationMeta(GType api, Structure params);

void addAllocationParam(Allocator allocator, AllocationParams params);

void addAllocationPool(BufferPool pool, uint size, uint minBuffers, uint maxBuffers);

bool addBufferingRange(long start, long stop);

void addSchedulingMode(GstPadMode mode);

bool findAllocationMeta(GType api, uint index);

uint getNAllocationMetas();

uint getNAllocationParams();

uint getNAllocationPools();

uint getNBufferingRanges();

uint getNSchedulingModes();

Structure getStructure();

bool hasSchedulingMode(GstPadMode mode);

bool hasSchedulingModeWithFlags(GstPadMode mode, GstSchedulingFlags flags);

void parseAcceptCaps(Caps caps);

void parseAcceptCapsResult(bool result);

void parseAllocation(Caps caps, bool needPool);

void parseBitrate(uint nominalBitrate);

void parseBufferingPercent(bool busy, int percent);

void parseBufferingRange(GstFormat format, long start, long stop, long estimatedTotal);

void parseBufferingStats(GstBufferingMode mode, int avgIn, int avgOut, long bufferingLeft);

void parseCaps(Caps filter);

void parseCapsResult(Caps caps);

void parseContext(Context context);

bool parseContextType(string contextType);

void parseConvert(GstFormat srcFormat, long srcValue, GstFormat destFormat, long destValue);

void parseDuration(GstFormat format, long duration);

void parseLatency(bool live, GstClockTime minLatency, GstClockTime maxLatency);

void parseNFormats(uint nFormats);

GType parseNthAllocationMeta(uint index, Structure params);

void parseNthAllocationParam(uint index, Allocator allocator, AllocationParams params);

void parseNthAllocationPool(uint index, BufferPool pool, uint size, uint minBuffers, uint maxBuffers);

bool parseNthBufferingRange(uint index, long start, long stop);

void parseNthFormat(uint nth, GstFormat format);

GstPadMode parseNthSchedulingMode(uint index);

void parsePosition(GstFormat format, long cur);

void parseScheduling(GstSchedulingFlags flags, int minsize, int maxsize, int align_);

void parseSeeking(GstFormat format, bool seekable, long segmentStart, long segmentEnd);

void parseSegment(double rate, GstFormat format, long startValue, long stopValue);

void parseUri(string uri);

void parseUriRedirection(string uri);

void parseUriRedirectionPermanent(bool permanent);

void removeNthAllocationMeta(uint index);

void removeNthAllocationParam(uint index);

void removeNthAllocationPool(uint index);

void setAcceptCapsResult(bool result);

void setBitrate(uint nominalBitrate);

void setBufferingPercent(bool busy, int percent);

void setBufferingRange(GstFormat format, long start, long stop, long estimatedTotal);

void setBufferingStats(GstBufferingMode mode, int avgIn, int avgOut, long bufferingLeft);

void setCapsResult(Caps caps);

void setContext(Context context);

void setConvert(GstFormat srcFormat, long srcValue, GstFormat destFormat, long destValue);

void setDuration(GstFormat format, long duration);

void setFormatsv(GstFormat[] formats);

void setLatency(bool live, GstClockTime minLatency, GstClockTime maxLatency);

void setNthAllocationParam(uint index, Allocator allocator, AllocationParams params);

void setNthAllocationPool(uint index, BufferPool pool, uint size, uint minBuffers, uint maxBuffers);

void setPosition(GstFormat format, long cur);

void setScheduling(GstSchedulingFlags flags, int minsize, int maxsize, int align_);

void setSeeking(GstFormat format, bool seekable, long segmentStart, long segmentEnd);

void setSegment(double rate, GstFormat format, long startValue, long stopValue);

void setUri(string uri);

void setUriRedirection(string uri);

void setUriRedirectionPermanent(bool permanent);

Structure writableStructure();

static GstQueryTypeFlags typeGetFlags(GstQueryType type);

static string typeGetName(GstQueryType type);

static GQuark typeToQuark(GstQueryType type);

}

Constructors

this this(GstQuery* gstQuery, bool ownedRef): Sets our main struct and passes it to the parent class.
this this(Caps caps, bool needPool): Constructs a new query object for querying the allocation properties.
this this(): Constructs a new query object for querying the bitrate.
this this(GstFormat format): Constructs a new query object for querying the buffering status of a stream.
this this(Caps filter): Constructs a new query object for querying the caps.
this this(string contextType): Constructs a new query object for querying the pipeline-local context.
this this(GstFormat srcFormat, long value, GstFormat destFormat): Constructs a new convert query object. Use Query.unref when done with it. A convert query is used to ask for a conversion between one format and another.
this this(GstQueryType type, Structure structure): Constructs a new custom query object. Use Query.unref when done with it.

Members

Functions

addAllocationMeta void addAllocationMeta(GType api, Structure params): Add api with params as one of the supported metadata API to query.
addAllocationParam void addAllocationParam(Allocator allocator, AllocationParams params): Add allocator and its params as a supported memory allocator.
addAllocationPool void addAllocationPool(BufferPool pool, uint size, uint minBuffers, uint maxBuffers): Set the pool parameters in query.
addBufferingRange bool addBufferingRange(long start, long stop): Set the buffering-ranges array field in query. The current last start position of the array should be inferior to start.
addSchedulingMode void addSchedulingMode(GstPadMode mode): Add mode as one of the supported scheduling modes to query.
findAllocationMeta bool findAllocationMeta(GType api, uint index): Check if query has metadata api set. When this function returns TRUE, index will contain the index where the requested API and the parameters can be found.
getNAllocationMetas uint getNAllocationMetas(): Retrieve the number of values currently stored in the meta API array of the query's structure.
getNAllocationParams uint getNAllocationParams(): Retrieve the number of values currently stored in the allocator params array of the query's structure.
getNAllocationPools uint getNAllocationPools(): Retrieve the number of values currently stored in the pool array of the query's structure.
getNBufferingRanges uint getNBufferingRanges(): Retrieve the number of values currently stored in the buffered-ranges array of the query's structure.
getNSchedulingModes uint getNSchedulingModes(): Retrieve the number of values currently stored in the scheduling mode array of the query's structure.
getQueryStruct GstQuery* getQueryStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
getStructure Structure getStructure(): Get the structure of a query.
hasSchedulingMode bool hasSchedulingMode(GstPadMode mode): Check if query has scheduling mode set.
hasSchedulingModeWithFlags bool hasSchedulingModeWithFlags(GstPadMode mode, GstSchedulingFlags flags): Check if query has scheduling mode set and flags is set in query scheduling flags.
parseAcceptCaps void parseAcceptCaps(Caps caps): Get the caps from query. The caps remains valid as long as query remains valid.
parseAcceptCapsResult void parseAcceptCapsResult(bool result): Parse the result from query and store in result.
parseAllocation void parseAllocation(Caps caps, bool needPool): Parse an allocation query, writing the requested caps in caps and whether a pool is needed in need_pool, if the respective parameters are non-NULL.
parseBitrate void parseBitrate(uint nominalBitrate): Get the results of a bitrate query. See also Query.setBitrate.
parseBufferingPercent void parseBufferingPercent(bool busy, int percent): Get the percentage of buffered data. This is a value between 0 and 100. The busy indicator is TRUE when the buffering is in progress.
parseBufferingRange void parseBufferingRange(GstFormat format, long start, long stop, long estimatedTotal): Parse an available query, writing the format into format, and other results into the passed parameters, if the respective parameters are non-NULL
parseBufferingStats void parseBufferingStats(GstBufferingMode mode, int avgIn, int avgOut, long bufferingLeft): Extracts the buffering stats values from query.
parseCaps void parseCaps(Caps filter): Get the filter from the caps query. The caps remains valid as long as query remains valid.
parseCapsResult void parseCapsResult(Caps caps): Get the caps result from query. The caps remains valid as long as query remains valid.
parseContext void parseContext(Context context): Get the context from the context query. The context remains valid as long as query remains valid.
parseContextType bool parseContextType(string contextType): Parse a context type from an existing GST_QUERY_CONTEXT query.
parseConvert void parseConvert(GstFormat srcFormat, long srcValue, GstFormat destFormat, long destValue): Parse a convert query answer. Any of src_format, src_value, dest_format, and dest_value may be NULL, in which case that value is omitted.
parseDuration void parseDuration(GstFormat format, long duration): Parse a duration query answer. Write the format of the duration into format, and the value into duration, if the respective variables are non-NULL.
parseLatency void parseLatency(bool live, GstClockTime minLatency, GstClockTime maxLatency): Parse a latency query answer.
parseNFormats void parseNFormats(uint nFormats): Parse the number of formats in the formats query.
parseNthAllocationMeta GType parseNthAllocationMeta(uint index, Structure params): Parse an available query and get the metadata API at index of the metadata API array.
parseNthAllocationParam void parseNthAllocationParam(uint index, Allocator allocator, AllocationParams params): Parse an available query and get the allocator and its params at index of the allocator array.
parseNthAllocationPool void parseNthAllocationPool(uint index, BufferPool pool, uint size, uint minBuffers, uint maxBuffers): Get the pool parameters in query.
parseNthBufferingRange bool parseNthBufferingRange(uint index, long start, long stop): Parse an available query and get the start and stop values stored at the index of the buffered ranges array.
parseNthFormat void parseNthFormat(uint nth, GstFormat format): Parse the format query and retrieve the nth format from it into format. If the list contains less elements than nth, format will be set to GST_FORMAT_UNDEFINED.
parseNthSchedulingMode GstPadMode parseNthSchedulingMode(uint index): Parse an available query and get the scheduling mode at index of the scheduling modes array.
parsePosition void parsePosition(GstFormat format, long cur): Parse a position query, writing the format into format, and the position into cur, if the respective parameters are non-NULL.
parseScheduling void parseScheduling(GstSchedulingFlags flags, int minsize, int maxsize, int align_): Set the scheduling properties.
parseSeeking void parseSeeking(GstFormat format, bool seekable, long segmentStart, long segmentEnd): Parse a seeking query, writing the format into format, and other results into the passed parameters, if the respective parameters are non-NULL
parseSegment void parseSegment(double rate, GstFormat format, long startValue, long stopValue): Parse a segment query answer. Any of rate, format, start_value, and stop_value may be NULL, which will cause this value to be omitted.
parseUri void parseUri(string uri): Parse an URI query, writing the URI into uri as a newly allocated string, if the respective parameters are non-NULL. Free the string with g_free() after usage.
parseUriRedirection void parseUriRedirection(string uri): Parse an URI query, writing the URI into uri as a newly allocated string, if the respective parameters are non-NULL. Free the string with g_free() after usage.
parseUriRedirectionPermanent void parseUriRedirectionPermanent(bool permanent): Parse an URI query, and set permanent to TRUE if there is a redirection and it should be considered permanent. If a redirection is permanent, applications should update their internal storage of the URI, otherwise they should make all future requests to the original URI.
removeNthAllocationMeta void removeNthAllocationMeta(uint index): Remove the metadata API at index of the metadata API array.
removeNthAllocationParam void removeNthAllocationParam(uint index): Remove the allocation param at index of the allocation param array.
removeNthAllocationPool void removeNthAllocationPool(uint index): Remove the allocation pool at index of the allocation pool array.
setAcceptCapsResult void setAcceptCapsResult(bool result): Set result as the result for the query.
setBitrate void setBitrate(uint nominalBitrate): Set the results of a bitrate query. The nominal bitrate is the average bitrate expected over the length of the stream as advertised in file headers (or similar).
setBufferingPercent void setBufferingPercent(bool busy, int percent): Set the percentage of buffered data. This is a value between 0 and 100. The busy indicator is TRUE when the buffering is in progress.
setBufferingRange void setBufferingRange(GstFormat format, long start, long stop, long estimatedTotal): Set the available query result fields in query.
setBufferingStats void setBufferingStats(GstBufferingMode mode, int avgIn, int avgOut, long bufferingLeft): Configures the buffering stats values in query.
setCapsResult void setCapsResult(Caps caps): Set the caps result in query.
setContext void setContext(Context context): Answer a context query by setting the requested context.
setConvert void setConvert(GstFormat srcFormat, long srcValue, GstFormat destFormat, long destValue): Answer a convert query by setting the requested values.
setDuration void setDuration(GstFormat format, long duration): Answer a duration query by setting the requested value in the given format.
setFormatsv void setFormatsv(GstFormat[] formats): Set the formats query result fields in query. The number of formats passed in the formats array must be equal to n_formats.
setLatency void setLatency(bool live, GstClockTime minLatency, GstClockTime maxLatency): Answer a latency query by setting the requested values in the given format.
setNthAllocationParam void setNthAllocationParam(uint index, Allocator allocator, AllocationParams params): Parse an available query and get the allocator and its params at index of the allocator array.
setNthAllocationPool void setNthAllocationPool(uint index, BufferPool pool, uint size, uint minBuffers, uint maxBuffers): Set the pool parameters in query.
setPosition void setPosition(GstFormat format, long cur): Answer a position query by setting the requested value in the given format.
setScheduling void setScheduling(GstSchedulingFlags flags, int minsize, int maxsize, int align_): Set the scheduling properties.
setSeeking void setSeeking(GstFormat format, bool seekable, long segmentStart, long segmentEnd): Set the seeking query result fields in query.
setSegment void setSegment(double rate, GstFormat format, long startValue, long stopValue): Answer a segment query by setting the requested values. The normal playback segment of a pipeline is 0 to duration at the default rate of 1.0. If a seek was performed on the pipeline to play a different segment, this query will return the range specified in the last seek.
setUri void setUri(string uri): Answer a URI query by setting the requested URI.
setUriRedirection void setUriRedirection(string uri): Answer a URI query by setting the requested URI redirection.
setUriRedirectionPermanent void setUriRedirectionPermanent(bool permanent): Answer a URI query by setting the requested URI redirection to permanent or not.
writableStructure Structure writableStructure(): Get the structure of a query. This method should be called with a writable query so that the returned structure is guaranteed to be writable.

Static functions

getType GType getType()
newAcceptCaps Query newAcceptCaps(Caps caps): Constructs a new query object for querying if caps are accepted. Free-function: gst_query_unref
newDrain Query newDrain(): Constructs a new query object for querying the drain state. Free-function: gst_query_unref
newDuration Query newDuration(GstFormat format): Constructs a new stream duration query object to query in the given format. Use Query.unref when done with it. A duration query will give the total length of the stream.
newFormats Query newFormats(): Constructs a new query object for querying formats of the stream.
newLatency Query newLatency(): Constructs a new latency query object. Use Query.unref when done with it. A latency query is usually performed by sinks to compensate for additional latency introduced by elements in the pipeline. Free-function: gst_query_unref
newPosition Query newPosition(GstFormat format): Constructs a new query stream position query object. Use Query.unref when done with it. A position query is used to query the current position of playback in the streams, in some format.
newScheduling Query newScheduling(): Constructs a new query object for querying the scheduling properties. Free-function: gst_query_unref
newSeeking Query newSeeking(GstFormat format): Constructs a new query object for querying seeking properties of the stream.
newSegment Query newSegment(GstFormat format): Constructs a new segment query object. Use Query.unref when done with it. A segment query is used to discover information about the currently configured segment for playback.
newUri Query newUri(): Constructs a new query URI query object. Use Query.unref when done with it. An URI query is used to query the current URI that is used by the source or sink. Free-function: gst_query_unref
typeGetFlags GstQueryTypeFlags typeGetFlags(GstQueryType type): Gets the GstQueryTypeFlags associated with type.
typeGetName string typeGetName(GstQueryType type): Get a printable name for the given query type. Do not modify or free.
typeToQuark GQuark typeToQuark(GstQueryType type): Get the unique quark for the given query type.

Variables

gstQuery GstQuery* gstQuery;: the main Gtk struct

gstreamer Query classes

Query