*
* @defgroup lavf_encoding Muxing
* @{
+ * Muxers take encoded data in the form of @ref AVPacket "AVPackets" and write
+ * it into files or other output bytestreams in the specified container format.
+ *
+ * The main API functions for muxing are avformat_write_header() for writing the
+ * file header, av_write_frame() / av_interleaved_write_frame() for writing the
+ * packets and av_write_trailer() for finalizing the file.
+ *
+ * At the beginning of the muxing process, the caller must first call
+ * avformat_alloc_context() to create a muxing context. The caller then sets up
+ * the muxer by filling the various fields in this context:
+ *
+ * - The @ref AVFormatContext.oformat "oformat" field must be set to select the
+ * muxer that will be used.
+ * - Unless the format is of the AVFMT_NOFILE type, the @ref AVFormatContext.pb
+ * "pb" field must be set to an opened IO context, either returned from
+ * avio_open2() or a custom one.
+ * - Unless the format is of the AVFMT_NOSTREAMS type, at least one stream must
+ * be created with the avformat_new_stream() function. The caller should fill
+ * the @ref AVStream.codec "stream codec context" information, such as the
+ * codec @ref AVCodecContext.codec_type "type", @ref AVCodecContext.codec_id
+ * "id" and other parameters (e.g. width / height, the pixel or sample format,
+ * etc.) as known. The @ref AVStream.time_base "stream timebase" should
+ * be set to the timebase that the caller desires to use for this stream (note
+ * that the timebase actually used by the muxer can be different, as will be
+ * described later).
+ * - It is advised to manually initialize only the relevant fields in
+ * AVCodecContext, rather than using @ref avcodec_copy_context() during
+ * remuxing: there is no guarantee that the codec context values remain valid
+ * for both input and output format contexts.
+ * - The caller may fill in additional information, such as @ref
+ * AVFormatContext.metadata "global" or @ref AVStream.metadata "per-stream"
+ * metadata, @ref AVFormatContext.chapters "chapters", @ref
+ * AVFormatContext.programs "programs", etc. as described in the
+ * AVFormatContext documentation. Whether such information will actually be
+ * stored in the output depends on what the container format and the muxer
+ * support.
+ *
+ * When the muxing context is fully set up, the caller must call
+ * avformat_write_header() to initialize the muxer internals and write the file
+ * header. Whether anything actually is written to the IO context at this step
+ * depends on the muxer, but this function must always be called. Any muxer
+ * private options must be passed in the options parameter to this function.
+ *
+ * The data is then sent to the muxer by repeatedly calling av_write_frame() or
+ * av_interleaved_write_frame() (consult those functions' documentation for
+ * discussion on the difference between them; only one of them may be used with
+ * a single muxing context, they should not be mixed). Do note that the timing
+ * information on the packets sent to the muxer must be in the corresponding
+ * AVStream's timebase. That timebase is set by the muxer (in the
+ * avformat_write_header() step) and may be different from the timebase
+ * requested by the caller.
+ *
+ * Once all the data has been written, the caller must call av_write_trailer()
+ * to flush any buffered packets and finalize the output file, then close the IO
+ * context (if any) and finally free the muxing context with
+ * avformat_free_context().
* @}
*
* @defgroup lavf_io I/O Read/Write
* - sorting -- a modified version of a tag that should be used for
* sorting will have '-sort' appended. E.g. artist="The Beatles",
* artist-sort="Beatles, The".
+ * - Some protocols and demuxers support metadata updates. After a successful
+ * call to av_read_packet(), AVFormatContext.event_flags or AVStream.event_flags
+ * will be updated to indicate if metadata changed. In order to detect metadata
+ * changes on a stream, you need to loop through all streams in the AVFormatContext
+ * and check their individual event_flags.
*
* - Demuxers attempt to export metadata in a generic format, however tags
* with no generic equivalents are left as they are stored in the container.
* Allocate and read the payload of a packet and initialize its
* fields with default values.
*
+ * @param s associated IO context
* @param pkt packet
* @param size desired payload size
* @return >0 (read size) if OK, AVERROR_xxx otherwise
* when there is no reasonable way to know (an upper bound of)
* the final size.
*
+ * @param s associated IO context
* @param pkt packet
* @param size amount of data to read
* @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
*/
int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
+#if FF_API_LAVF_FRAC
/*************************************************/
/* fractional numbers for exact pts handling */
typedef struct AVFrac {
int64_t val, num, den;
} AVFrac;
+#endif
/*************************************************/
/* input/output formats */
const char *filename;
unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
int buf_size; /**< Size of buf except extra allocated bytes */
+ const char *mime_type; /**< mime_type, when known. */
} AVProbeData;
#define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
+#define AVPROBE_SCORE_MIME 75 ///< score for file mime type
#define AVPROBE_SCORE_MAX 100 ///< maximum score
#define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
const AVClass *priv_class; ///< AVClass for the private context
+ /**
+ * Comma-separated list of mime types.
+ * It is used check for matching mime types while probing.
+ * @see av_probe_input_format2
+ */
+ const char *mime_type;
+
/*****************************************************************
* No fields below this line are part of the public API. They
* may not be used outside of libavformat and can be changed and
/**
* Read the format header and initialize the AVFormatContext
- * structure. Return 0 if OK. Only used in raw format right
- * now. 'avformat_new_stream' should be called to create new streams.
+ * structure. Return 0 if OK. 'avformat_new_stream' should be
+ * called to create new streams.
*/
int (*read_header)(struct AVFormatContext *);
AVCodecContext *codec;
void *priv_data;
+#if FF_API_LAVF_FRAC
/**
- * encoding: pts generation when outputting stream
+ * @deprecated this field is unused
*/
+ attribute_deprecated
struct AVFrac pts;
+#endif
/**
* This is the fundamental unit of time (in seconds) in terms
* of which frame timestamps are represented.
*
* decoding: set by libavformat
- * encoding: set by libavformat in avformat_write_header. The muxer may use the
- * user-provided value of @ref AVCodecContext.time_base "codec->time_base"
- * as a hint.
+ * encoding: May be set by the caller before avformat_write_header() to
+ * provide a hint to the muxer about the desired timebase. In
+ * avformat_write_header(), the muxer will overwrite this field
+ * with the timebase that will actually be used for the timestamps
+ * written into the file (which may or may not be related to the
+ * user-provided one, depending on the format).
*/
AVRational time_base;
/**
* Average framerate
+ *
+ * - demuxing: May be set by libavformat when creating the stream or in
+ * avformat_find_stream_info().
+ * - muxing: May be set by the caller before avformat_write_header().
*/
AVRational avg_frame_rate;
*/
AVPacket attached_pic;
+ /**
+ * An array of side data that applies to the whole stream (i.e. the
+ * container does not allow it to change between packets).
+ *
+ * There may be no overlap between the side data in this array and side data
+ * in the packets. I.e. a given side data is either exported by the muxer
+ * (demuxing) / set by the caller (muxing) in this array, then it never
+ * appears in the packets, or the side data is exported / sent through
+ * the packets (always in the first packet where the value becomes known or
+ * changes), then it does not appear in this array.
+ *
+ * - demuxing: Set by libavformat when the stream is created.
+ * - muxing: May be set by the caller before avformat_write_header().
+ *
+ * Freed by libavformat in avformat_free_context().
+ */
+ AVPacketSideData *side_data;
+ /**
+ * The number of elements in the AVStream.side_data array.
+ */
+ int nb_side_data;
+
+ /**
+ * Flags for the user to detect events happening on the stream. Flags must
+ * be cleared by the user once the event has been handled.
+ * A combination of AVSTREAM_EVENT_FLAG_*.
+ */
+ int event_flags;
+#define AVSTREAM_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
+
/*****************************************************************
* All fields below this line are not part of the public API. They
* may not be used outside of libavformat and can be changed and
int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
-#if FF_API_REFERENCE_DTS
- /* a hack to keep ABI compatibility for avconv, which accesses parser even
- * though it should not */
- int64_t do_not_use;
-#endif
// Timestamp generation support:
int64_t first_dts;
int64_t cur_dts;
*/
typedef struct AVFormatContext {
/**
- * A class for logging and AVOptions. Set by avformat_alloc_context().
+ * A class for logging and @ref avoptions. Set by avformat_alloc_context().
* Exports (de)muxer private options if they exist.
*/
const AVClass *av_class;
/**
- * Can only be iformat or oformat, not both at the same time.
+ * The input container format.
*
- * decoding: set by avformat_open_input().
- * encoding: set by the user.
+ * Demuxing only, set by avformat_open_input().
*/
struct AVInputFormat *iformat;
+
+ /**
+ * The output container format.
+ *
+ * Muxing only, must be set by the caller before avformat_write_header().
+ */
struct AVOutputFormat *oformat;
/**
* Format private data. This is an AVOptions-enabled struct
* if and only if iformat/oformat.priv_class is not NULL.
+ *
+ * - muxing: set by avformat_write_header()
+ * - demuxing: set by avformat_open_input()
*/
void *priv_data;
/**
* I/O context.
*
- * decoding: either set by the user before avformat_open_input() (then
- * the user must close it manually) or set by avformat_open_input().
- * encoding: set by the user.
+ * - demuxing: either set by the user before avformat_open_input() (then
+ * the user must close it manually) or set by avformat_open_input().
+ * - muxing: set by the user before avformat_write_header(). The caller must
+ * take care of closing / freeing the IO context.
*
* Do NOT set this field if AVFMT_NOFILE flag is set in
* iformat/oformat.flags. In such a case, the (de)muxer will handle
AVIOContext *pb;
/* stream info */
- int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */
+ /**
+ * Flags signalling stream properties. A combination of AVFMTCTX_*.
+ * Set by libavformat.
+ */
+ int ctx_flags;
+ /**
+ * Number of elements in AVFormatContext.streams.
+ *
+ * Set by avformat_new_stream(), must not be modified by any other code.
+ */
+ unsigned int nb_streams;
/**
* A list of all streams in the file. New streams are created with
* avformat_new_stream().
*
- * decoding: streams are created by libavformat in avformat_open_input().
- * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
- * appear in av_read_frame().
- * encoding: streams are created by the user before avformat_write_header().
+ * - demuxing: streams are created by libavformat in avformat_open_input().
+ * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
+ * appear in av_read_frame().
+ * - muxing: streams are created by the user before avformat_write_header().
+ *
+ * Freed by libavformat in avformat_free_context().
*/
- unsigned int nb_streams;
AVStream **streams;
- char filename[1024]; /**< input or output filename */
+ /**
+ * input or output filename
+ *
+ * - demuxing: set by avformat_open_input()
+ * - muxing: may be set by the caller before avformat_write_header()
+ */
+ char filename[1024];
/**
- * Decoding: position of the first frame of the component, in
+ * Position of the first frame of the component, in
* AV_TIME_BASE fractional seconds. NEVER set this value directly:
* It is deduced from the AVStream values.
+ *
+ * Demuxing only, set by libavformat.
*/
int64_t start_time;
/**
- * Decoding: duration of the stream, in AV_TIME_BASE fractional
+ * Duration of the stream, in AV_TIME_BASE fractional
* seconds. Only set this value if you know none of the individual stream
* durations and also do not set any of them. This is deduced from the
* AVStream values if not set.
+ *
+ * Demuxing only, set by libavformat.
*/
int64_t duration;
/**
- * Decoding: total stream bitrate in bit/s, 0 if not
+ * Total stream bitrate in bit/s, 0 if not
* available. Never set it directly if the file_size and the
* duration are known as Libav can compute it automatically.
*/
unsigned int packet_size;
int max_delay;
+ /**
+ * Flags modifying the (de)muxer behaviour. A combination of AVFMT_FLAG_*.
+ * Set by the user before avformat_open_input() / avformat_write_header().
+ */
int flags;
#define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
#define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
#define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
#define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
#define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
+/**
+ * When muxing, try to avoid writing any random/volatile data to the output.
+ * This includes any random IDs, real-time timestamps/dates, muxer version, etc.
+ *
+ * This flag is mainly intended for testing.
+ */
+#define AVFMT_FLAG_BITEXACT 0x0400
/**
- * decoding: size of data to probe; encoding: unused.
+ * Maximum size of the data read from input for determining
+ * the input container format.
+ * Demuxing only, set by the caller before avformat_open_input().
*/
unsigned int probesize;
/**
- * decoding: maximum time (in AV_TIME_BASE units) during which the input should
- * be analyzed in avformat_find_stream_info().
+ * Maximum duration (in AV_TIME_BASE units) of the data read
+ * from input in avformat_find_stream_info().
+ * Demuxing only, set by the caller before avformat_find_stream_info().
*/
int max_analyze_duration;
* accurate seeking (depends on demuxer).
* Demuxers for which a full in-memory index is mandatory will ignore
* this.
- * muxing : unused
- * demuxing: set by user
+ * - muxing: unused
+ * - demuxing: set by user
*/
unsigned int max_index_size;
* in the trailer. To write chapters in the trailer, nb_chapters
* must be zero when write_header is called and non-zero when
* write_trailer is called.
- * muxing : set by user
- * demuxing: set by libavformat
+ * - muxing: set by user
+ * - demuxing: set by libavformat
*/
unsigned int nb_chapters;
AVChapter **chapters;
+ /**
+ * Metadata that applies to the whole file.
+ *
+ * - demuxing: set by libavformat in avformat_open_input()
+ * - muxing: may be set by the caller before avformat_write_header()
+ *
+ * Freed by libavformat in avformat_free_context().
+ */
AVDictionary *metadata;
/**
* Start time of the stream in real world time, in microseconds
- * since the unix epoch (00:00 1st January 1970). That is, pts=0
- * in the stream was captured at this real world time.
- * - encoding: Set by user.
- * - decoding: Unused.
+ * since the Unix epoch (00:00 1st January 1970). That is, pts=0 in the
+ * stream was captured at this real world time.
+ * Muxing only, set by the caller before avformat_write_header().
*/
int64_t start_time_realtime;
/**
- * decoding: number of frames used to probe fps
+ * The number of frames used for determining the framerate in
+ * avformat_find_stream_info().
+ * Demuxing only, set by the caller before avformat_find_stream_info().
*/
int fps_probe_size;
/**
* Error recognition; higher values will detect more errors but may
* misdetect some more or less valid parts as errors.
- * - encoding: unused
- * - decoding: Set by user.
+ * Demuxing only, set by the caller before avformat_open_input().
*/
int error_recognition;
/**
* Custom interrupt callbacks for the I/O layer.
*
- * decoding: set by the user before avformat_open_input().
- * encoding: set by the user before avformat_write_header()
+ * demuxing: set by the user before avformat_open_input().
+ * muxing: set by the user before avformat_write_header()
* (mainly useful for AVFMT_NOFILE formats). The callback
* should also be passed to avio_open2() if it's used to
* open the file.
*/
int64_t max_interleave_delta;
- /*****************************************************************
- * All fields below this line are not part of the public API. They
- * may not be used outside of libavformat and can be changed and
- * removed at will.
- * New public fields should be added right above.
- *****************************************************************
- */
-
/**
- * This buffer is only needed when packets were already buffered but
- * not decoded, for example to get the codec parameters in MPEG
- * streams.
+ * Allow non-standard and experimental extension
+ * @see AVCodecContext.strict_std_compliance
*/
- struct AVPacketList *packet_buffer;
- struct AVPacketList *packet_buffer_end;
-
- /* av_seek_frame() support */
- int64_t data_offset; /**< offset of the first packet */
+ int strict_std_compliance;
/**
- * Raw packets from the demuxer, prior to parsing and decoding.
- * This buffer is used for buffering packets until the codec can
- * be identified, as parsing cannot be done without knowing the
- * codec.
- */
- struct AVPacketList *raw_packet_buffer;
- struct AVPacketList *raw_packet_buffer_end;
- /**
- * Packets split by the parser get queued here.
+ * Flags for the user to detect events happening on the file. Flags must
+ * be cleared by the user once the event has been handled.
+ * A combination of AVFMT_EVENT_FLAG_*.
*/
- struct AVPacketList *parse_queue;
- struct AVPacketList *parse_queue_end;
- /**
- * Remaining size available for raw_packet_buffer, in bytes.
- */
-#define RAW_PACKET_BUFFER_SIZE 2500000
- int raw_packet_buffer_remaining_size;
+ int event_flags;
+#define AVFMT_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
/**
- * Offset to remap timestamps to be non-negative.
- * Expressed in timebase units.
+ * Maximum number of packets to read while waiting for the first timestamp.
+ * Decoding only.
*/
- int64_t offset;
+ int max_ts_probe;
/**
- * Timebase for the timestamp offset.
+ * Avoid negative timestamps during muxing.
+ * Any value of the AVFMT_AVOID_NEG_TS_* constants.
+ * Note, this only works when using av_interleaved_write_frame.
+ * - muxing: Set by user
+ * - demuxing: unused
*/
- AVRational offset_timebase;
+ int avoid_negative_ts;
+#define AVFMT_AVOID_NEG_TS_AUTO -1 ///< Enabled when required by target format
+#define AVFMT_AVOID_NEG_TS_MAKE_NON_NEGATIVE 1 ///< Shift timestamps so they are non negative
+#define AVFMT_AVOID_NEG_TS_MAKE_ZERO 2 ///< Shift timestamps so that they start at 0
/**
* An opaque field for libavformat internal usage.
* if f is non-NULL, returns the next registered input format after f
* or NULL if f is the last one.
*/
-AVInputFormat *av_iformat_next(AVInputFormat *f);
+AVInputFormat *av_iformat_next(const AVInputFormat *f);
/**
* If f is NULL, returns the first registered output format,
* if f is non-NULL, returns the next registered output format after f
* or NULL if f is the last one.
*/
-AVOutputFormat *av_oformat_next(AVOutputFormat *f);
+AVOutputFormat *av_oformat_next(const AVOutputFormat *f);
/**
* Allocate an AVFormatContext.
*
* When muxing, should be called by the user before avformat_write_header().
*
+ * @param s media file handle
* @param c If non-NULL, the AVCodecContext corresponding to the new stream
* will be initialized to use this codec. This is needed for e.g. codec-specific
* defaults to be set, so codec should be provided if it is known.
*
* @return newly created stream or NULL on error.
*/
-AVStream *avformat_new_stream(AVFormatContext *s, AVCodec *c);
+AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c);
+
+/**
+ * Get side information from stream.
+ *
+ * @param stream stream
+ * @param type desired side information type
+ * @param size pointer for side information size to store (optional)
+ * @return pointer to data if present or NULL otherwise
+ */
+uint8_t *av_stream_get_side_data(AVStream *stream,
+ enum AVPacketSideDataType type, int *size);
AVProgram *av_new_program(AVFormatContext *s, int id);
/**
* Guess the file format.
*
+ * @param pd data to be probed
* @param is_opened Whether the file is already opened; determines whether
* demuxers with or without AVFMT_NOFILE are probed.
*/
/**
* Guess the file format.
*
+ * @param pd data to be probed
* @param is_opened Whether the file is already opened; determines whether
* demuxers with or without AVFMT_NOFILE are probed.
* @param score_max A probe score larger that this is required to accept a
/**
* Seek to the keyframe at timestamp.
* 'timestamp' in 'stream_index'.
+ *
+ * @param s media file handle
* @param stream_index If stream_index is (-1), a default
* stream is selected, and timestamp is automatically converted
* from AV_TIME_BASE units to the stream specific time_base.
* If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
* keyframes (this may not be supported by all demuxers).
*
+ * @param s media file handle
* @param stream_index index of the stream which is used as time base reference
* @param min_ts smallest acceptable timestamp
* @param ts target timestamp
* function.
*
* @param s media file handle
- * @param pkt @parblock
- * The packet containing the data to be written. Note that unlike
+ * @param pkt The packet containing the data to be written. Note that unlike
* av_interleaved_write_frame(), this function does not take
* ownership of the packet passed to it (though some muxers may make
* an internal reference to the input packet).
- *
+ * <br>
* This parameter can be NULL (at any time, not just at the end), in
* order to immediately flush data buffered within the muxer, for
* muxers that buffer up data internally before writing it to the
* output.
- *
+ * <br>
* Packet's @ref AVPacket.stream_index "stream_index" field must be
* set to the index of the corresponding stream in @ref
* AVFormatContext.streams "s->streams". It is very strongly
* recommended that timing information (@ref AVPacket.pts "pts", @ref
* AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
* correct values.
- * @endparblock
* @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
*
* @see av_interleaved_write_frame()
* av_write_frame() instead of this function.
*
* @param s media file handle
- * @param pkt @parblock
- * The packet containing the data to be written.
- *
+ * @param pkt The packet containing the data to be written.
+ * <br>
* If the packet is reference-counted, this function will take
* ownership of this reference and unreference it later when it sees
* fit.
* The caller must not access the data through this reference after
* this function returns. If the packet is not reference-counted,
* libavformat will make a copy.
- *
+ * <br>
* This parameter can be NULL (at any time, not just at the end), to
* flush the interleaving queues.
- *
+ * <br>
* Packet's @ref AVPacket.stream_index "stream_index" field must be
* set to the index of the corresponding stream in @ref
* AVFormatContext.streams "s->streams". It is very strongly
* recommended that timing information (@ref AVPacket.pts "pts", @ref
* AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
* correct values.
- * @endparblock
*
- * @return 0 on success, a negative AVERROR on error.
+ * @return 0 on success, a negative AVERROR on error. Libavformat will always
+ * take care of freeing the packet, even if this function fails.
*
* @see av_write_frame(), AVFormatContext.max_interleave_delta
*/
*
* @param tags list of supported codec_id-codec_tag pairs, as stored
* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
+ * @param tag codec tag to match to a codec ID
*/
enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
*
* @param tags list of supported codec_id-codec_tag pairs, as stored
* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
+ * @param id codec ID to match to a codec tag
*/
unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
/**
* Get the index for a specific timestamp.
+ *
+ * @param st stream that the timestamp belongs to
+ * @param timestamp timestamp to retrieve the index for
* @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
* to the timestamp which is <= the requested one, if backward
* is 0, then it will be >=
const char *url);
+/**
+ * Print detailed information about the input or output format, such as
+ * duration, bitrate, streams, container, programs, metadata, side data,
+ * codec and time base.
+ *
+ * @param ic the context to analyze
+ * @param index the index to print, if you have multiple inputs or outputs
+ * @param url the URL to print, such as source or destination file
+ * @param is_output whether the context is input or ouput
+ */
void av_dump_format(AVFormatContext *ic,
int index,
const char *url,
* Return a positive value if the given filename has one of the given
* extensions, 0 otherwise.
*
+ * @param filename file name to check against the given extensions
* @param extensions a comma-separated list of filename extensions
*/
int av_match_ext(const char *filename, const char *extensions);
/**
* Test if the given container can store a codec.
*
+ * @param ofmt container to check for compatibility
+ * @param codec_id codec to potentially store in container
* @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
*
* @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
* A negative number if this information is not available.
*/
-int avformat_query_codec(AVOutputFormat *ofmt, enum AVCodecID codec_id, int std_compliance);
+int avformat_query_codec(const AVOutputFormat *ofmt, enum AVCodecID codec_id,
+ int std_compliance);
/**
* @defgroup riff_fourcc RIFF FourCCs