mirror of https://code.videolan.org/videolan/vlc
103 lines
3.3 KiB
C
103 lines
3.3 KiB
C
/*****************************************************************************
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* vlc_timestamp_helper.h : timestamp handling helpers
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*****************************************************************************
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* Copyright (C) 2014 VLC authors and VideoLAN
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*
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* Authors: Felix Abecassis <felix.abecassis@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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#ifndef VLC_TIMESTAMP_H
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#define VLC_TIMESTAMP_H 1
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#include <vlc_tick.h>
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/* Implementation of a circular buffer of timestamps with overwriting
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* of older values. MediaCodec has only one type of timestamp, if a
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* block has no PTS, we send the DTS instead. Some hardware decoders
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* cannot cope with this situation and output the frames in the wrong
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* order. As a workaround in this case, we use a FIFO of timestamps in
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* order to remember which input packets had no PTS. Since an
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* hardware decoder can silently drop frames, this might cause a
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* growing desynchronization with the actual timestamp. Thus the
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* circular buffer has a limited size and will overwrite older values.
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*/
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typedef struct
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{
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uint32_t begin;
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uint32_t size;
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uint32_t capacity;
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vlc_tick_t *buffer;
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} timestamp_fifo_t;
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static inline timestamp_fifo_t *timestamp_FifoNew(uint32_t capacity)
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{
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timestamp_fifo_t *fifo = (timestamp_fifo_t *)calloc(1, sizeof(*fifo));
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if (!fifo)
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return NULL;
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fifo->buffer = (vlc_tick_t*)vlc_alloc(capacity, sizeof(*fifo->buffer));
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if (!fifo->buffer) {
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free(fifo);
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return NULL;
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}
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fifo->capacity = capacity;
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return fifo;
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}
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static inline void timestamp_FifoRelease(timestamp_fifo_t *fifo)
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{
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free(fifo->buffer);
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free(fifo);
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}
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static inline bool timestamp_FifoIsEmpty(timestamp_fifo_t *fifo)
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{
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return fifo->size == 0;
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}
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static inline bool timestamp_FifoIsFull(timestamp_fifo_t *fifo)
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{
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return fifo->size == fifo->capacity;
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}
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static inline void timestamp_FifoEmpty(timestamp_fifo_t *fifo)
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{
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fifo->size = 0;
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}
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static inline void timestamp_FifoPut(timestamp_fifo_t *fifo, vlc_tick_t ts)
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{
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uint32_t end = (fifo->begin + fifo->size) % fifo->capacity;
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fifo->buffer[end] = ts;
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if (!timestamp_FifoIsFull(fifo))
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fifo->size += 1;
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else
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fifo->begin = (fifo->begin + 1) % fifo->capacity;
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}
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static inline vlc_tick_t timestamp_FifoGet(timestamp_fifo_t *fifo)
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{
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if (timestamp_FifoIsEmpty(fifo))
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return VLC_TICK_INVALID;
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vlc_tick_t result = fifo->buffer[fifo->begin];
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fifo->begin = (fifo->begin + 1) % fifo->capacity;
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fifo->size -= 1;
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return result;
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}
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#endif
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