From ddd551e06d838ea7edd8bbcb985b047391c30557 Mon Sep 17 00:00:00 2001
From: "Timothy B. Terriberry" <tterribe@xiph.org>
Date: Sun, 9 Sep 2012 03:13:26 -0700
Subject: [PATCH] Add documentation for the repacketizer API.
This patch also includes some small edits for the main API
documentation.
---
include/opus.h | 291 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 283 insertions(+), 8 deletions(-)
diff --git a/include/opus.h b/include/opus.h
index a1f0156fe..9de31af64 100644
--- a/include/opus.h
+++ b/include/opus.h
@@ -161,6 +161,11 @@ extern "C" {
*/
typedef struct OpusEncoder OpusEncoder;
+/** Gets the size of an OpusEncoder structure.
+ * @param[in] channels <tt>int</tt>: Number of channels.
+ * This must be 1 or 2.
+ * @returns The size in bytes.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_encoder_get_size(int channels);
/**
@@ -351,8 +356,9 @@ OPUS_EXPORT int opus_encoder_ctl(OpusEncoder *st, int request, ...) OPUS_ARG_NON
typedef struct OpusDecoder OpusDecoder;
/** Gets the size of an OpusDecoder structure.
- * @param [in] channels <tt>int</tt>: Number of channels
- * @returns size
+ * @param [in] channels <tt>int</tt>: Number of channels.
+ * This must be 1 or 2.
+ * @returns The size in bytes.
*/
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_decoder_get_size(int channels);
@@ -479,10 +485,13 @@ OPUS_EXPORT int opus_packet_parse(
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_packet_get_bandwidth(const unsigned char *data) OPUS_ARG_NONNULL(1);
/** Gets the number of samples per frame from an Opus packet.
- * @param [in] data <tt>char*</tt>: Opus packet
- * @param [in] Fs <tt>opus_int32</tt>: Sampling rate in Hz
- * @returns Number of samples per frame
- * @retval OPUS_INVALID_PACKET The compressed data passed is corrupted or of an unsupported type
+ * @param [in] data <tt>char*</tt>: Opus packet.
+ * This must contain at least one byte of
+ * data.
+ * @param [in] Fs <tt>opus_int32</tt>: Sampling rate in Hz.
+ * This must be a multiple of 400, or
+ * inaccurate results will be returned.
+ * @returns Number of samples per frame.
*/
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_packet_get_samples_per_frame(const unsigned char *data, opus_int32 Fs) OPUS_ARG_NONNULL(1);
@@ -514,27 +523,293 @@ OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_decoder_get_nb_samples(const OpusDe
/** @defgroup opus_repacketizer Repacketizer
* @{
*
- * The repacketizer can be used to merge multiple Opus packets into a single packet
- * or alternatively to split Opus packets that have previously been merged.
+ * The repacketizer can be used to merge multiple Opus packets into a single
+ * packet or alternatively to split Opus packets that have previously been
+ * merged. The repacketizer currently only operates on elementary Opus
+ * streams. It will not manipualte multistream packets successfully, except in
+ * the degenerate case where they consist of data from a single stream.
+ *
+ * The repacketizing process starts with creating a repacketizer state, either
+ * by calling opus_repacketizer_create() or by allocating the memory yourself,
+ * e.g.,
+ * @code
+ * OpusRepacketizer *rp;
+ * rp = (OpusRepacketizer*)malloc(opus_repacketizer_get_size());
+ * if (rp != NULL)
+ * opus_repacketizer_init(rp);
+ * @endcode
+ *
+ * Then the application should submit packets with opus_repacketizer_cat(),
+ * extract new packets with opus_repacketizer_out() or
+ * opus_repacketizer_out_range(), and then reset the state for the next set of
+ * input packets via opus_repacketizer_init().
+ *
+ * For example, to split a sequence of packets into individual frames:
+ * @code
+ * unsigned char *data;
+ * int len;
+ * while (get_next_packet(&data, &len))
+ * {
+ * unsigned char out[1276];
+ * opus_int32 out_len;
+ * int nb_frames;
+ * int err;
+ * int i;
+ * err = opus_repacketizer_cat(rp, data, len);
+ * if (err != OPUS_OK)
+ * {
+ * release_packet(data);
+ * return err;
+ * }
+ * nb_frames = opus_repacketizer_get_nb_frames(rp);
+ * for (i = 0; i < nb_frames; i++)
+ * {
+ * out_len = opus_repacketizer_out_range(rp, i, i+1, out, sizeof(out));
+ * if (out_len < 0)
+ * {
+ * release_packet(data);
+ * return (int)out_len;
+ * }
+ * output_next_packet(out, out_len);
+ * }
+ * opus_repacketizer_init(rp);
+ * release_packet(data);
+ * }
+ * @endcode
*
+ * Alternatively, to combine a sequence of frames into packets that each
+ * contain up to <code>TARGET_DURATION_MS</code> milliseconds of data:
+ * @code
+ * // The maximum number of packets with duration TARGET_DURATION_MS occurs
+ * // when the frame size is 2.5 ms, for a total of (TARGET_DURATION_MS*5/2)
+ * // packets.
+ * unsigned char *data[(TARGET_DURATION_MS*5/2)+1];
+ * opus_int32 len[(TARGET_DURATION_MS*5/2)+1];
+ * int nb_packets;
+ * unsigned char out[1277*(TARGET_DURATION_MS*5/2)];
+ * opus_int32 out_len;
+ * int prev_toc;
+ * nb_packets = 0;
+ * while (get_next_packet(data+nb_packets, len+nb_packets))
+ * {
+ * int nb_frames;
+ * int err;
+ * nb_frames = opus_packet_get_nb_frames(data[nb_packets], len[nb_packets]);
+ * if (nb_frames < 1)
+ * {
+ * release_packets(data, nb_packets+1);
+ * return nb_frames;
+ * }
+ * nb_frames += opus_repacketizer_get_nb_frames(rp);
+ * // If adding the next packet would exceed our target, or it has an
+ * // incompatible TOC sequence, output the packets we already have before
+ * // submitting it.
+ * // N.B., The nb_packets > 0 check ensures we've submitted at least one
+ * // packet since the last call to opus_repacketizer_init(). Otherwise a
+ * // single packet longer than TARGET_DURATION_MS would cause us to try to
+ * // output an (invalid) empty packet. It also ensures that prev_toc has
+ * // been set to a valid value. Additionally, len[nb_packets] > 0 is
+ * // guaranteed by the call to opus_packet_get_nb_frames() above, so the
+ * // reference to data[nb_packets][0] should be valid.
+ * if (nb_packets > 0 && (
+ * ((prev_toc & 0xFC) != (data[nb_packets][0] & 0xFC)) ||
+ * opus_packet_get_samples_per_frame(data[nb_packets], 2000)*nb_frames >
+ * TARGET_DURATION_MS*2))
+ * {
+ * out_len = opus_repacketizer_out(rp, out, sizeof(out));
+ * if (out_len < 0)
+ * {
+ * release_packets(data, nb_packets+1);
+ * return (int)out_len;
+ * }
+ * output_next_packet(out, out_len);
+ * opus_repacketizer_init(rp);
+ * release_packets(data, nb_packets);
+ * data[0] = data[nb_packets];
+ * len[0] = len[nb_packets];
+ * nb_packets = 0;
+ * }
+ * err = opus_repacketizer_cat(rp, data[nb_packets], len[nb_packets]);
+ * if (err != OPUS_OK)
+ * {
+ * release_packets(data, nb_packets+1);
+ * return err;
+ * }
+ * prev_toc = data[nb_packets][0];
+ * nb_packets++;
+ * }
+ * // Output the final, partial packet.
+ * if (nb_packets > 0)
+ * {
+ * out_len = opus_repacketizer_out(rp, out, sizeof(out));
+ * release_packets(data, nb_packets);
+ * if (out_len < 0)
+ * return (int)out_len;
+ * output_next_packet(out, out_len);
+ * }
+ * @endcode
*/
typedef struct OpusRepacketizer OpusRepacketizer;
+/** Gets the size of an <code>OpusRepacketizer</code> structure.
+ * @returns The size in bytes.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_repacketizer_get_size(void);
+/** (Re)initializes a previously allocated repacketizer state.
+ * The state must be the size returned by opus_repacketizer_get_size().
+ * This can be used for applications which use their own allocator instead of
+ * malloc().
+ * It must also be called to reset the queue of packets waiting to be
+ * repacketized, which is necessary if the maximum packet duration of 120 ms
+ * is reached or if you wish to submit packets with a different Opus
+ * configuration (coding mode, audio bandwidth, frame size, or channel count).
+ * Failure to do so will prevent a new packet from being added with
+ * opus_repacketizer_cat().
+ * @see opus_repacketizer_create
+ * @see opus_repacketizer_get_size
+ * @see opus_repacketizer_cat
+ * @param rp <tt>OpusRepacketizer*</tt>: The repacketizer state to
+ * (re)initialize.
+ * @returns A pointer to the same repacketizer state that was passed in.
+ */
OPUS_EXPORT OpusRepacketizer *opus_repacketizer_init(OpusRepacketizer *rp) OPUS_ARG_NONNULL(1);
+/** Allocates and initializes a repacketizer state.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT OpusRepacketizer *opus_repacketizer_create(void);
+/** Frees an <code>OpusRepacketizer</code> allocated by
+ * opus_repacketizer_create().
+ * @param[in] rp <tt>OpusRepacketizer*</tt>: State to be freed.
+ */
OPUS_EXPORT void opus_repacketizer_destroy(OpusRepacketizer *rp);
+/** Add a packet to the current repacketizer state.
+ * This packet must match the configuration of any packets already submitted
+ * for repacketization since the last call to opus_repacketizer_init().
+ * This means that it must have the same coding mode, audio bandwidth, frame
+ * size, and channel count.
+ * This can be checked in advance by examining the top 6 bits of the first
+ * byte of the packet, and ensuring they match the top 6 bits of the first
+ * byte of any previously submitted packet.
+ * The total duration of audio in the repacketizer state also must not exceed
+ * 120 ms, the maximum duration of a single packet, after adding this packet.
+ *
+ * The contents of the current repacketizer state can be extracted into new
+ * packets using opus_repacketizer_out() or opus_repacketizer_out_range().
+ *
+ * In order to add a packet with a different configuration or to add more
+ * audio beyond 120 ms, you must clear the repacketizer state by calling
+ * opus_repacketizer_init().
+ * If a packet is too large to add to the current repacketizer state, no part
+ * of it is added, even if it contains multiple frames, some of which might
+ * fit.
+ * If you wish to be able to add parts of such packets, you should first use
+ * another repacketizer to split the packet into pieces and add them
+ * individually.
+ * @see opus_repacketizer_out_range
+ * @see opus_repacketizer_out
+ * @see opus_repacketizer_init
+ * @param rp <tt>OpusRepacketizer*</tt>: The repacketizer state to which to
+ * add the packet.
+ * @param[in] data <tt>const unsigned char*</tt>: The packet data.
+ * The application must ensure
+ * this pointer remains valid
+ * until the next call to
+ * opus_repacketizer_init() or
+ * opus_repacketizer_destroy().
+ * @param len <tt>opus_int32</tt>: The number of bytes in the packet data.
+ * @returns An error code indicating whether or not the operation succeeded.
+ * @retval #OPUS_OK The packet's contents have been added to the repacketizer
+ * state.
+ * @retval #OPUS_INVALID_PACKET The packet did not have a valid TOC sequence,
+ * the packet's TOC sequence was not compatible
+ * with previously submitted packets (because
+ * the coding mode, audio bandwidth, frame size,
+ * or channel count did not match), or adding
+ * this packet would increase the total amount of
+ * audio stored in the repacketizer state to more
+ * than 120 ms.
+ */
OPUS_EXPORT int opus_repacketizer_cat(OpusRepacketizer *rp, const unsigned char *data, opus_int32 len) OPUS_ARG_NONNULL(1) OPUS_ARG_NONNULL(2);
+
+/** Construct a new packet from data previously submitted to the repacketizer
+ * state via opus_repacketizer_cat().
+ * @param rp <tt>OpusRepacketizer*</tt>: The repacketizer state from which to
+ * construct the new packet.
+ * @param begin <tt>int</tt>: The index of the first frame in the current
+ * repacketizer state to include in the output.
+ * @param end <tt>int</tt>: One past the index of the last frame in the
+ * current repacketizer state to include in the
+ * output.
+ * @param[out] data <tt>const unsigned char*</tt>: The buffer in which to
+ * store the output packet.
+ * @param maxlen <tt>opus_int32</tt>: The maximum number of bytes to store in
+ * the output buffer. In order to guarantee
+ * success, this should be at least
+ * <code>1276</code> for a single frame,
+ * or for multiple frames,
+ * <code>1277*(end-begin)</code>.
+ * However, <code>1*(end-begin)</code> plus
+ * the size of all packet data submitted to
+ * the repacketizer since the last call to
+ * opus_repacketizer_init() or
+ * opus_repacketizer_create() is also
+ * sufficient, and possibly much smaller.
+ * @returns The total size of the output packet on success, or an error code
+ * on failure.
+ * @retval #OPUS_BAD_ARG <code>[begin,end)</code> was an invalid range of
+ * frames (begin < 0, begin >= end, or end >
+ * opus_repacketizer_get_nb_frames()).
+ * @retval #OPUS_BUFFER_TOO_SMALL \a maxlen was insufficient to contain the
+ * complete output packet.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT opus_int32 opus_repacketizer_out_range(OpusRepacketizer *rp, int begin, int end, unsigned char *data, opus_int32 maxlen) OPUS_ARG_NONNULL(1) OPUS_ARG_NONNULL(4);
+/** Return the total number of frames contained in packet data submitted to
+ * the repacketizer state so far via opus_repacketizer_cat() since the last
+ * call to opus_repacketizer_init() or opus_repacketizer_create().
+ * This defines the valid range of packets that can be extracted with
+ * opus_repacketizer_out_range() or opus_repacketizer_out().
+ * @param rp <tt>OpusRepacketizer*</tt>: The repacketizer state containing the
+ * frames.
+ * @returns The total number of frames contained in the packet data submitted
+ * to the repacketizer state.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT int opus_repacketizer_get_nb_frames(OpusRepacketizer *rp) OPUS_ARG_NONNULL(1);
+/** Construct a new packet from data previously submitted to the repacketizer
+ * state via opus_repacketizer_cat().
+ * This is a convenience routine that returns all the data submitted so far
+ * in a single packet.
+ * It is equivalent to calling
+ * @code
+ * opus_repacketizer_out_range(rp, 0, opus_repacketizer_get_nb_frames(rp),
+ * data, maxlen)
+ * @endcode
+ * @param rp <tt>OpusRepacketizer*</tt>: The repacketizer state from which to
+ * construct the new packet.
+ * @param[out] data <tt>const unsigned char*</tt>: The buffer in which to
+ * store the output packet.
+ * @param maxlen <tt>opus_int32</tt>: The maximum number of bytes to store in
+ * the output buffer. In order to guarantee
+ * success, this should be at least
+ * <code>1277*opus_repacketizer_get_nb_frames(rp)</code>.
+ * However,
+ * <code>1*opus_repacketizer_get_nb_frames(rp)</code>
+ * plus the size of all packet data
+ * submitted to the repacketizer since the
+ * last call to opus_repacketizer_init() or
+ * opus_repacketizer_create() is also
+ * sufficient, and possibly much smaller.
+ * @returns The total size of the output packet on success, or an error code
+ * on failure.
+ * @retval #OPUS_BUFFER_TOO_SMALL \a maxlen was insufficient to contain the
+ * complete output packet.
+ */
OPUS_EXPORT OPUS_WARN_UNUSED_RESULT opus_int32 opus_repacketizer_out(OpusRepacketizer *rp, unsigned char *data, opus_int32 maxlen) OPUS_ARG_NONNULL(1);
/**@}*/
--
GitLab