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ffmpeg.wasm-core
Commit 7a656933 authored by Ivan Schreter's avatar Ivan Schreter
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cosmetic changes (indentation, doxygen comments, braces, put structures for API to header, ...) 

Originally committed as revision 19773 to svn://svn.ffmpeg.org/ffmpeg/trunk
parent 64b8e620
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Showing with 142 additions and 141 deletions
libavformat/seek.c
View file @ 7a656933
/*
* Utility functions for seeking for use within FFmpeg format handlers.
* seek utility functions for use within format handlers
*
* Copyright (c) 2009 Ivan Schreter
*
......@@ -28,65 +28,33 @@
extern void av_read_frame_flush(AVFormatContext *s);
/**
* Helper structure to store parser state of AVStream.
*/
typedef struct AVStreamState {
// Saved members of AVStream
AVCodecParserContext *parser;
AVPacket cur_pkt;
int64_t last_IP_pts;
int64_t cur_dts;
int64_t reference_dts;
const uint8_t *cur_ptr;
int cur_len;
int probe_packets;
} AVStreamState;
/**
* Helper structure to store parser state of AVFormat.
*/
struct AVParserState {
int64_t fpos; ///< File position at the time of call.
// Saved members of AVFormatContext
AVStream *cur_st; ///< Current stream.
AVPacketList *packet_buffer; ///< Packet buffer of original state.
AVPacketList *raw_packet_buffer; ///< Raw packet buffer of original state.
int raw_packet_buffer_remaining_size; ///< Remaining size available for raw_packet_buffer.
// Saved info for streams.
int nb_streams; ///< Number of streams with stored state.
AVStreamState *stream_states; ///< States of individual streams (array).
};
/**
* Helper structure describing keyframe search state of one stream.
* helper structure describing keyframe search state of one stream
*/
typedef struct {
int64_t pos_lo; ///< Position of the frame with low timestamp in file or INT64_MAX if not found (yet).
int64_t ts_lo; ///< Frame presentation timestamp or same as pos_lo for byte seeking.
int64_t pos_lo; ///< position of the frame with low timestamp in file or INT64_MAX if not found (yet)
int64_t ts_lo; ///< frame presentation timestamp or same as pos_lo for byte seeking
int64_t pos_hi; ///< Position of the frame with high timestamp in file or INT64_MAX if not found (yet).
int64_t ts_hi; ///< Frame presentation timestamp or same as pos_hi for byte seeking.
int64_t pos_hi; ///< position of the frame with high timestamp in file or INT64_MAX if not found (yet)
int64_t ts_hi; ///< frame presentation timestamp or same as pos_hi for byte seeking
int64_t last_pos; ///< Last known position of a frame, for multi-frame packets.
int64_t last_pos; ///< last known position of a frame, for multi-frame packets
int64_t term_ts; ///< Termination timestamp (which TS we already read).
AVRational term_ts_tb; ///< Timebase for term_ts.
int64_t first_ts; ///< First packet timestamp in this iteration (to fill term_ts later).
AVRational first_ts_tb;///< Timebase for first_ts.
int64_t term_ts; ///< termination timestamp (which TS we already read)
AVRational term_ts_tb; ///< timebase for term_ts
int64_t first_ts; ///< first packet timestamp in this iteration (to fill term_ts later)
AVRational first_ts_tb; ///< timebase for first_ts
int terminated; ///< Termination flag for current iteration.
int terminated; ///< termination flag for the current iteration
} AVSyncPoint;
/**
* Compare two timestamps exactly, taking into account their respective time bases.
* Compare two timestamps exactly, taking their respective time bases into account.
*
* @param ts_a timestamp A.
* @param tb_a time base for timestamp A.
* @param ts_b timestamp B.
* @param tb_b time base for timestamp A.
* @return -1. 0 or 1 if timestamp A is less than, equal or greater than timestamp B.
* @param ts_a timestamp A
* @param tb_a time base for timestamp A
* @param ts_b timestamp B
* @param tb_b time base for timestamp A
* @return -1, 0 or 1 if timestamp A is less than, equal or greater than timestamp B
*/
static int compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
{
......@@ -95,9 +63,9 @@ static int compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb
if (ts_a == INT64_MIN)
return ts_a < ts_b ? -1 : 0;
if (ts_a == INT64_MAX)
return ts_a > ts_b ? 1 : 0;
return ts_a > ts_b ? 1 : 0;
if (ts_b == INT64_MIN)
return ts_a > ts_b ? 1 : 0;
return ts_a > ts_b ? 1 : 0;
if (ts_b == INT64_MAX)
return ts_a < ts_b ? -1 : 0;
......@@ -105,7 +73,7 @@ static int compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb
b = ts_b * tb_b.num * tb_a.den;
res = a - b;
if (res == 0)
if (!res)
return 0;
else
return (res >> 63) | 1;
......@@ -117,13 +85,16 @@ static int compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb
* Distances are only comparable, if same time bases are used for computing
* distances.
*
* @param ts_hi high timestamp.
* @param tb_hi high timestamp time base.
* @param ts_lo low timestamp.
* @param tb_lo low timestamp time base.
* @return representation of distance between high and low timestamps.
* @param ts_hi high timestamp
* @param tb_hi high timestamp time base
* @param ts_lo low timestamp
* @param tb_lo low timestamp time base
* @return representation of distance between high and low timestamps
*/
static int64_t ts_distance(int64_t ts_hi, AVRational tb_hi, int64_t ts_lo, AVRational tb_lo)
static int64_t ts_distance(int64_t ts_hi,
AVRational tb_hi,
int64_t ts_lo,
AVRational tb_lo)
{
int64_t hi, lo;
......@@ -136,23 +107,23 @@ static int64_t ts_distance(int64_t ts_hi, AVRational tb_hi, int64_t ts_lo, AVRat
/**
* Partial search for keyframes in multiple streams.
*
* This routine searches for the next lower and next higher timestamp to
* given target timestamp in each stream, starting at current file position
* and ending at position, where all streams have already been examined
* (or when all higher key frames found in first iteration).
* This routine searches in each stream for the next lower and the next higher
* timestamp compared to the given target timestamp. The search starts at the current
* file position and ends at the file position, where all streams have already been
* examined (or when all higher key frames are found in the first iteration).
*
* This routine is called iteratively with exponential backoff to find lower
* This routine is called iteratively with an exponential backoff to find the lower
* timestamp.
*
* @param s format context.
* @param timestamp target timestamp (or position, if AVSEEK_FLAG_BYTE).
* @param timebase time base for timestamps.
* @param flags seeking flags.
* @param sync array with information per stream.
* @param keyframes_to_find count of keyframes to find in total.
* @param found_lo pointer to count of already found low timestamp keyframes.
* @param found_hi pointer to count of already found high timestamp keyframes.
* @param first_iter flag for first iteration.
* @param s format context
* @param timestamp target timestamp (or position, if AVSEEK_FLAG_BYTE)
* @param timebase time base for timestamps
* @param flags seeking flags
* @param sync array with information per stream
* @param keyframes_to_find count of keyframes to find in total
* @param found_lo ptr to the count of already found low timestamp keyframes
* @param found_hi ptr to the count of already found high timestamp keyframes
* @param first_iter flag for first iteration
*/
static void search_hi_lo_keyframes(AVFormatContext *s,
int64_t timestamp,
......@@ -182,7 +153,7 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
if (s->streams[idx]->discard < AVDISCARD_ALL) {
sp = &sync[idx];
if (sp->pos_hi == INT64_MAX) {
// No high frame exists for this stream
// no high frame exists for this stream
(*found_hi)++;
sp->ts_hi = INT64_MAX;
sp->pos_hi = INT64_MAX - 1;
......@@ -194,20 +165,20 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
idx = pkt.stream_index;
st = s->streams[idx];
if (st->discard >= AVDISCARD_ALL) {
// This stream is not active, skip packet.
if (st->discard >= AVDISCARD_ALL)
// this stream is not active, skip packet
continue;
}
sp = &sync[idx];
flg = pkt.flags;
pos = pkt.pos;
pts = pkt.pts;
dts = pkt.dts;
if (pts == AV_NOPTS_VALUE) {
// Some formats don't provide PTS, only DTS.
if (pts == AV_NOPTS_VALUE)
// some formats don't provide PTS, only DTS
pts = dts;
}
av_free_packet(&pkt);
// Multi-frame packets only return position for the very first frame.
......@@ -216,21 +187,21 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
// position arrives. In this way, it's possible to seek to proper
// position. Additionally, for parsers not providing position at all,
// an approximation will be used (starting position of this iteration).
if (pos < 0) {
if (pos < 0)
pos = sp->last_pos;
} else {
else
sp->last_pos = pos;
}
// Evaluate key frames with known TS (or any frames, if AVSEEK_FLAG_ANY set).
if (pts != AV_NOPTS_VALUE && ((flg & PKT_FLAG_KEY) || (flags & AVSEEK_FLAG_ANY))) {
if (pts != AV_NOPTS_VALUE &&
((flg & PKT_FLAG_KEY) || (flags & AVSEEK_FLAG_ANY))) {
if (flags & AVSEEK_FLAG_BYTE) {
// For byte seeking, use position as timestamp.
// for byte seeking, use position as timestamp
ts = pos;
ts_tb.num = 1;
ts_tb.den = 1;
} else {
// Get stream time_base.
// otherwise, get stream time_base
ts = pts;
ts_tb = st->time_base;
}
......@@ -244,13 +215,14 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
sp->first_ts_tb = ts_tb;
}
if (sp->term_ts != AV_NOPTS_VALUE && compare_ts(ts, ts_tb, sp->term_ts, sp->term_ts_tb) > 0) {
// We are past the end position from last iteration, ignore packet.
if (sp->term_ts != AV_NOPTS_VALUE &&
compare_ts(ts, ts_tb, sp->term_ts, sp->term_ts_tb) > 0) {
// past the end position from last iteration, ignore packet
if (!sp->terminated) {
sp->terminated = 1;
++terminated_count;
if (sp->pos_hi == INT64_MAX) {
// No high frame exists for this stream
// no high frame exists for this stream
(*found_hi)++;
sp->ts_hi = INT64_MAX;
sp->pos_hi = INT64_MAX - 1;
......@@ -262,22 +234,22 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
}
if (compare_ts(ts, ts_tb, timestamp, timebase) <= 0) {
// Keyframe found before target timestamp.
// keyframe found before target timestamp
if (sp->pos_lo == INT64_MAX) {
// Found first keyframe lower than target timestamp.
// found first keyframe lower than target timestamp
(*found_lo)++;
sp->ts_lo = ts;
sp->pos_lo = pos;
} else if (sp->ts_lo < ts) {
// Found a better match (closer to target timestamp).
// found a better match (closer to target timestamp)
sp->ts_lo = ts;
sp->pos_lo = pos;
}
}
if (compare_ts(ts, ts_tb, timestamp, timebase) >= 0) {
// Keyframe found after target timestamp.
// keyframe found after target timestamp
if (sp->pos_hi == INT64_MAX) {
// Found first keyframe higher than target timestamp.
// found first keyframe higher than target timestamp
(*found_hi)++;
sp->ts_hi = ts;
sp->pos_hi = pos;
......@@ -288,7 +260,7 @@ static void search_hi_lo_keyframes(AVFormatContext *s,
break;
}
} else if (sp->ts_hi > ts) {
// Found a better match (actually, shouldn't happen).
// found a better match (actually, shouldn't happen)
sp->ts_hi = ts;
sp->pos_hi = pos;
}
......@@ -321,27 +293,27 @@ int64_t ff_gen_syncpoint_search(AVFormatContext *s,
AVRational time_base;
if (flags & AVSEEK_FLAG_BYTE) {
/* For byte seeking, we have exact 1:1 "timestamps" - positions */
// for byte seeking, we have exact 1:1 "timestamps" - positions
time_base.num = 1;
time_base.den = 1;
} else {
if (stream_index >= 0) {
/* We have a reference stream, which time base we use */
// we have a reference stream, which time base we use
st = s->streams[stream_index];
time_base = st->time_base;
} else {
/* No reference stream, use AV_TIME_BASE as reference time base */
// no reference stream, use AV_TIME_BASE as reference time base
time_base.num = 1;
time_base.den = AV_TIME_BASE;
}
}
// Initialize syncpoint structures for each stream.
sync = (AVSyncPoint*) av_malloc(s->nb_streams * sizeof(AVSyncPoint));
if (!sync) {
sync = av_malloc(s->nb_streams * sizeof(AVSyncPoint));
if (!sync)
// cannot allocate helper structure
return -1;
}
for (i = 0; i < s->nb_streams; ++i) {
st = s->streams[i];
sp = &sync[i];
......@@ -362,8 +334,8 @@ int64_t ff_gen_syncpoint_search(AVFormatContext *s,
++keyframes_to_find;
}
if (keyframes_to_find == 0) {
// No stream active, error.
if (!keyframes_to_find) {
// no stream active, error
av_free(sync);
return -1;
}
......@@ -383,7 +355,7 @@ int64_t ff_gen_syncpoint_search(AVFormatContext *s,
first_iter);
if (found_lo == keyframes_to_find && found_hi == keyframes_to_find)
break; // have all keyframes we wanted
if (curpos == 0)
if (!curpos)
break; // cannot go back anymore
curpos = pos - step;
......@@ -454,12 +426,12 @@ AVParserState *ff_store_parser_state(AVFormatContext *s)
{
int i;
AVStream *st;
AVStreamState *ss;
AVParserState *state = (AVParserState*) av_malloc(sizeof(AVParserState));
AVParserStreamState *ss;
AVParserState *state = av_malloc(sizeof(AVParserState));
if (!state)
return NULL;
state->stream_states = (AVStreamState*) av_malloc(sizeof(AVStreamState) * s->nb_streams);
state->stream_states = av_malloc(sizeof(AVParserStreamState) * s->nb_streams);
if (!state->stream_states) {
av_free(state);
return NULL;
......@@ -510,7 +482,7 @@ void ff_restore_parser_state(AVFormatContext *s, AVParserState *state)
{
int i;
AVStream *st;
AVStreamState *ss;
AVParserStreamState *ss;
av_read_frame_flush(s);
if (!state)
......@@ -557,7 +529,7 @@ static void free_packet_list(AVPacketList *pktl)
void ff_free_parser_state(AVFormatContext *s, AVParserState *state)
{
int i;
AVStreamState *ss;
AVParserStreamState *ss;
if (!state)
return;
......
libavformat/seek.h
View file @ 7a656933
/*
* Utility functions for seeking for use within FFmpeg format handlers.
* seek utility functions for use within format handlers
*
* Copyright (c) 2009 Ivan Schreter
*
......@@ -25,30 +25,59 @@
#include "avformat.h"
/// Opaque structure for parser state.
typedef struct AVParserState AVParserState;
/**
* structure to store parser state of one AVStream
*/
typedef struct AVParserStreamState {
// saved members of AVStream
AVCodecParserContext *parser;
AVPacket cur_pkt;
int64_t last_IP_pts;
int64_t cur_dts;
int64_t reference_dts;
const uint8_t *cur_ptr;
int cur_len;
int probe_packets;
} AVParserStreamState;
/**
* structure to store parser state of AVFormat
*/
typedef struct AVParserState {
int64_t fpos; ///< file position at the time of call
// saved members of AVFormatContext
AVStream *cur_st; ///< current stream.
AVPacketList *packet_buffer; ///< packet buffer of original state
AVPacketList *raw_packet_buffer; ///< raw packet buffer of original state
int raw_packet_buffer_remaining_size; ///< remaining space in raw_packet_buffer
// saved info for streams
int nb_streams; ///< number of streams with stored state
AVParserStreamState *stream_states; ///< states of individual streams (array)
} AVParserState;
/**
* Search for sync point of all active streams.
* Search for the sync point of all active streams.
*
* This is not supposed to be called directly by a user application,
* This routine is not supposed to be called directly by a user application,
* but by demuxers.
*
* A sync point is a point in stream, so that decoding from this point,
* output of decoders of all streams synchronizes closest to given timestamp
* ts (but taking timestamp limits into account, i.e., no sooner than ts_min
* and no later than ts_max).
* A sync point is defined as a point in stream, such that, when decoding start
* from this point, the decoded output of all streams synchronizes closest
* to the given timestamp ts. This routine also takes timestamp limits into account.
* Thus, the output will synchronize no sooner than ts_min and no later than ts_max.
*
* @param stream_index stream index for time base reference of timestamps.
* @param pos approximate position where to start searching for key frames.
* @param min_ts minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set).
* @param ts target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags).
* @param max_ts maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set).
* @param flags if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only
* to a keyframe. If AVSEEK_FLAG_BYTE is set, search by
* position, not by timestamp.
* @return < 0 if no such sync point could be found, otherwise stream position
* (stream is repositioned to this position).
* @param stream_index stream index for time base reference of timestamps
* @param pos approximate position where to start searching for key frames
* @param min_ts minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
* @param ts target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags)
* @param max_ts maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
* @param flags if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only
* to a keyframe. If AVSEEK_FLAG_BYTE is set, search by
* position, not by timestamp.
* @return -1 if no such sync point could be found, otherwise stream position
* (stream is repositioned to this position)
*/
int64_t ff_gen_syncpoint_search(AVFormatContext *s,
int stream_index,
......@@ -61,16 +90,16 @@ int64_t ff_gen_syncpoint_search(AVFormatContext *s,
/**
* Store current parser state and file position.
*
* This function can be used by demuxers before destructive seeking algorithm
* to store parser state. After the seek, depending on outcome, original state
* can be restored or new state kept and original state freed.
* This function can be used by demuxers before a destructive seeking algorithm
* to store the parser state. Depending on the outcome of the seek, either the original
* state can be restored or the new state kept and the original state freed.
*
* @note As a side effect, original parser state is reset, since structures
* are relinked to stored state instead of being deeply-copied (for
* performance reasons and to keep code simple).
* @note As a side effect, the original parser state is reset, since structures
* are relinked to the stored state instead of being deeply-copied (for
* performance reasons and to keep the code simple).
*
* @param s context from which to save state.
* @return parser state object or NULL if memory could not be allocated.
* @param s context from which to save state
* @return parser state object or NULL if memory could not be allocated
*/
AVParserState *ff_store_parser_state(AVFormatContext *s);
......@@ -78,19 +107,19 @@ AVParserState *ff_store_parser_state(AVFormatContext *s);
* Restore previously saved parser state and file position.
*
* Saved state will be invalidated and freed by this call, since internal
* structures will be relinked back to stored state instead of being
* structures will be relinked back to the stored state instead of being
* deeply-copied.
*
* @param s context to which to restore state (same as used for storing state).
* @param state state to restore.
* @param s context to which to restore state (same as used for storing state)
* @param state state to restore
*/
void ff_restore_parser_state(AVFormatContext *s, AVParserState *state);
/**
* Free previously saved parser state.
*
* @param s context to which the state belongs (same as used for storing state).
* @param state state to free.
* @param s context to which the state belongs (same as used for storing state)
* @param state state to free
*/
void ff_free_parser_state(AVFormatContext *s, AVParserState *state);
......
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