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https://github.com/mpv-player/mpv
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758f8f7bd4
This is a simplification, because it lets us use the AVPacket functions, instead of handling the details manually. It also allows the libavcodec rawvideo decoder to use reference counting, so it doesn't have to memcpy() the full image data. The change in av_common.c enables this. This change is somewhat risky, because we rely on the following AVPacket implementation details and assumptions: - av_packet_ref() doesn't access the input padding, and just copies the data. By the API, AVPacket is always padded, and we violate this. The lavc implementation would have to go out of its way to make this a real problem, though. - We hope that the way we make the AVPacket refcountable in av_common.c is actually supported API-usage. It's hard to tell whether it is. Of course we still use our own "old" demux_packet struct, just so that libav* API usage is somewhat isolated.
112 lines
3.3 KiB
C
112 lines
3.3 KiB
C
/*
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* This file is part of mpv.
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*
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* mpv is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* mpv 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with mpv. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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#include <libavcodec/avcodec.h>
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#include "common/av_common.h"
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#include "common/common.h"
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#include "packet.h"
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static void packet_destroy(void *ptr)
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{
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struct demux_packet *dp = ptr;
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av_packet_unref(dp->avpacket);
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}
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// This actually preserves only data and side data, not PTS/DTS/pos/etc.
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// It also allows avpkt->data==NULL with avpkt->size!=0 - the libavcodec API
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// does not allow it, but we do it to simplify new_demux_packet().
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struct demux_packet *new_demux_packet_from_avpacket(struct AVPacket *avpkt)
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{
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if (avpkt->size > 1000000000) {
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fprintf(stderr, "Attempt to allocate demux packet over 1 GB!\n");
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abort();
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}
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struct demux_packet *dp = talloc(NULL, struct demux_packet);
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talloc_set_destructor(dp, packet_destroy);
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*dp = (struct demux_packet) {
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.pts = MP_NOPTS_VALUE,
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.dts = MP_NOPTS_VALUE,
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.duration = -1,
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.pos = -1,
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.stream = -1,
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.avpacket = talloc_zero(dp, AVPacket),
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};
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av_init_packet(dp->avpacket);
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int r = -1;
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if (avpkt->data) {
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// We hope that this function won't need/access AVPacket input padding,
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// because otherwise new_demux_packet_from() wouldn't work.
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r = av_packet_ref(dp->avpacket, avpkt);
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} else {
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r = av_new_packet(dp->avpacket, avpkt->size);
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}
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if (r < 0) {
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fprintf(stderr, "Out of memory when referencing packet.\n");
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abort();
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}
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dp->buffer = dp->avpacket->data;
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dp->len = dp->avpacket->size;
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return dp;
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}
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// Input data doesn't need to be padded.
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struct demux_packet *new_demux_packet_from(void *data, size_t len)
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{
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AVPacket pkt = { .data = data, .size = len };
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return new_demux_packet_from_avpacket(&pkt);
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}
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struct demux_packet *new_demux_packet(size_t len)
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{
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assert(len <= INT_MAX);
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AVPacket pkt = { .data = NULL, .size = len };
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return new_demux_packet_from_avpacket(&pkt);
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}
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void demux_packet_shorten(struct demux_packet *dp, size_t len)
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{
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assert(len <= dp->len);
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dp->len = len;
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memset(dp->buffer + dp->len, 0, FF_INPUT_BUFFER_PADDING_SIZE);
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}
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void free_demux_packet(struct demux_packet *dp)
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{
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talloc_free(dp);
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}
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struct demux_packet *demux_copy_packet(struct demux_packet *dp)
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{
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struct demux_packet *new = NULL;
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if (dp->avpacket) {
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new = new_demux_packet_from_avpacket(dp->avpacket);
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} else {
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// Some packets might be not created by new_demux_packet*().
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new = new_demux_packet_from(dp->buffer, dp->len);
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}
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new->pts = dp->pts;
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new->dts = dp->dts;
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new->duration = dp->duration;
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return new;
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}
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