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librempeg/libavformat/ffmdec.c
Andreas Cadhalpun f6e1c96730 ffmdec: change type of len to ptrdiff_t 
It is used to store the difference between pointers, so ptrdiff_t is the
correct type.

This prevents potential overflows.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
2016-01-11 23:14:52 +01:00

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/*
* FFM (ffserver live feed) demuxer
* Copyright (c) 2001 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/intfloat.h"
#include "libavutil/opt.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "avformat.h"
#include "internal.h"
#include "ffm.h"
#include "avio_internal.h"
static int ffm_is_avail_data(AVFormatContext *s, int size)
{
FFMContext *ffm = s->priv_data;
int64_t pos, avail_size;
ptrdiff_t len;
len = ffm->packet_end - ffm->packet_ptr;
if (size <= len)
return 1;
pos = avio_tell(s->pb);
if (!ffm->write_index) {
if (pos == ffm->file_size)
return AVERROR_EOF;
avail_size = ffm->file_size - pos;
} else {
if (pos == ffm->write_index) {
/* exactly at the end of stream */
if (ffm->server_attached)
return AVERROR(EAGAIN);
else
return AVERROR_INVALIDDATA;
} else if (pos < ffm->write_index) {
avail_size = ffm->write_index - pos;
} else {
avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);
}
}
avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;
if (size <= avail_size)
return 1;
else if (ffm->server_attached)
return AVERROR(EAGAIN);
else
return AVERROR_INVALIDDATA;
}
static int ffm_resync(AVFormatContext *s, uint32_t state)
{
av_log(s, AV_LOG_ERROR, "resyncing\n");
while (state != PACKET_ID) {
if (avio_feof(s->pb)) {
av_log(s, AV_LOG_ERROR, "cannot find FFM syncword\n");
return -1;
}
state = (state << 8) | avio_r8(s->pb);
}
return 0;
}
/* first is true if we read the frame header */
static int ffm_read_data(AVFormatContext *s,
uint8_t *buf, int size, int header)
{
FFMContext *ffm = s->priv_data;
AVIOContext *pb = s->pb;
int fill_size, size1, frame_offset;
uint32_t id;
ptrdiff_t len;
int64_t last_pos = -1;
size1 = size;
while (size > 0) {
redo:
len = ffm->packet_end - ffm->packet_ptr;
if (len < 0)
return -1;
if (len > size)
len = size;
if (len == 0) {
if (avio_tell(pb) == ffm->file_size) {
if (ffm->server_attached) {
avio_seek(pb, ffm->packet_size, SEEK_SET);
} else
return AVERROR_EOF;
}
retry_read:
if (pb->buffer_size != ffm->packet_size) {
int64_t tell = avio_tell(pb);
int ret = ffio_set_buf_size(pb, ffm->packet_size);
if (ret < 0)
return ret;
avio_seek(pb, tell, SEEK_SET);
}
id = avio_rb16(pb); /* PACKET_ID */
if (id != PACKET_ID) {
if (ffm_resync(s, id) < 0)
return -1;
last_pos = avio_tell(pb);
}
fill_size = avio_rb16(pb);
ffm->dts = avio_rb64(pb);
frame_offset = avio_rb16(pb);
avio_read(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
if (ffm->packet_size < FFM_HEADER_SIZE + fill_size || frame_offset < 0) {
return -1;
}
ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
/* if first packet or resynchronization packet, we must
handle it specifically */
if (ffm->first_packet || (frame_offset & 0x8000)) {
if (!frame_offset) {
/* This packet has no frame headers in it */
if (avio_tell(pb) >= ffm->packet_size * 3LL) {
int64_t seekback = FFMIN(ffm->packet_size * 2LL, avio_tell(pb) - last_pos);
seekback = FFMAX(seekback, 0);
avio_seek(pb, -seekback, SEEK_CUR);
goto retry_read;
}
/* This is bad, we cannot find a valid frame header */
return 0;
}
ffm->first_packet = 0;
if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE) {
ffm->packet_end = ffm->packet_ptr;
return -1;
}
ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;
if (!header)
break;
} else {
ffm->packet_ptr = ffm->packet;
}
goto redo;
}
memcpy(buf, ffm->packet_ptr, len);
buf += len;
ffm->packet_ptr += len;
size -= len;
header = 0;
}
return size1 - size;
}
/* ensure that actual seeking happens between FFM_PACKET_SIZE
and file_size - FFM_PACKET_SIZE */
static int64_t ffm_seek1(AVFormatContext *s, int64_t pos1)
{
FFMContext *ffm = s->priv_data;
AVIOContext *pb = s->pb;
int64_t pos;
pos = FFMIN(pos1, ffm->file_size - FFM_PACKET_SIZE);
pos = FFMAX(pos, FFM_PACKET_SIZE);
ff_dlog(s, "seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);
return avio_seek(pb, pos, SEEK_SET);
}
static int64_t get_dts(AVFormatContext *s, int64_t pos)
{
AVIOContext *pb = s->pb;
int64_t dts;
ffm_seek1(s, pos);
avio_skip(pb, 4);
dts = avio_rb64(pb);
ff_dlog(s, "dts=%0.6f\n", dts / 1000000.0);
return dts;
}
static void adjust_write_index(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
AVIOContext *pb = s->pb;
int64_t pts;
//int64_t orig_write_index = ffm->write_index;
int64_t pos_min, pos_max;
int64_t pts_start;
int64_t ptr = avio_tell(pb);
pos_min = 0;
pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
pts_start = get_dts(s, pos_min);
pts = get_dts(s, pos_max);
if (pts - 100000 > pts_start)
goto end;
ffm->write_index = FFM_PACKET_SIZE;
pts_start = get_dts(s, pos_min);
pts = get_dts(s, pos_max);
if (pts - 100000 <= pts_start) {
while (1) {
int64_t newpos;
int64_t newpts;
newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
if (newpos == pos_min)
break;
newpts = get_dts(s, newpos);
if (newpts - 100000 <= pts) {
pos_max = newpos;
pts = newpts;
} else {
pos_min = newpos;
}
}
ffm->write_index += pos_max;
}
end:
avio_seek(pb, ptr, SEEK_SET);
}
static int ffm_close(AVFormatContext *s)
{
int i;
for (i = 0; i < s->nb_streams; i++)
av_freep(&s->streams[i]->codec->rc_eq);
return 0;
}
static int ffm_append_recommended_configuration(AVStream *st, char **conf)
{
int ret;
size_t newsize;
av_assert0(conf && st);
if (!*conf)
return 0;
if (!st->recommended_encoder_configuration) {
st->recommended_encoder_configuration = *conf;
*conf = 0;
return 0;
}
newsize = strlen(*conf) + strlen(st->recommended_encoder_configuration) + 2;
if ((ret = av_reallocp(&st->recommended_encoder_configuration, newsize)) < 0)
return ret;
av_strlcat(st->recommended_encoder_configuration, ",", newsize);
av_strlcat(st->recommended_encoder_configuration, *conf, newsize);
av_freep(conf);
return 0;
}
static int ffm2_read_header(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
AVStream *st;
AVIOContext *pb = s->pb;
AVCodecContext *codec;
const AVCodecDescriptor *codec_desc;
int ret;
int f_main = 0, f_cprv = -1, f_stvi = -1, f_stau = -1;
AVCodec *enc;
char *buffer;
ffm->packet_size = avio_rb32(pb);
if (ffm->packet_size != FFM_PACKET_SIZE) {
av_log(s, AV_LOG_ERROR, "Invalid packet size %d, expected size was %d\n",
ffm->packet_size, FFM_PACKET_SIZE);
ret = AVERROR_INVALIDDATA;
goto fail;
}
ffm->write_index = avio_rb64(pb);
/* get also filesize */
if (pb->seekable) {
ffm->file_size = avio_size(pb);
if (ffm->write_index && 0)
adjust_write_index(s);
} else {
ffm->file_size = (UINT64_C(1) << 63) - 1;
}
while(!avio_feof(pb)) {
unsigned id = avio_rb32(pb);
unsigned size = avio_rb32(pb);
int64_t next = avio_tell(pb) + size;
char rc_eq_buf[128];
if(!id)
break;
switch(id) {
case MKBETAG('M', 'A', 'I', 'N'):
if (f_main++) {
ret = AVERROR(EINVAL);
goto fail;
}
avio_rb32(pb); /* nb_streams */
avio_rb32(pb); /* total bitrate */
break;
case MKBETAG('C', 'O', 'M', 'M'):
f_cprv = f_stvi = f_stau = 0;
st = avformat_new_stream(s, NULL);
if (!st) {
ret = AVERROR(ENOMEM);
goto fail;
}
avpriv_set_pts_info(st, 64, 1, 1000000);
codec = st->codec;
/* generic info */
codec->codec_id = avio_rb32(pb);
codec_desc = avcodec_descriptor_get(codec->codec_id);
if (!codec_desc) {
av_log(s, AV_LOG_ERROR, "Invalid codec id: %d\n", codec->codec_id);
codec->codec_id = AV_CODEC_ID_NONE;
goto fail;
}
codec->codec_type = avio_r8(pb);
if (codec->codec_type != codec_desc->type) {
av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",
codec_desc->type, codec->codec_type);
codec->codec_id = AV_CODEC_ID_NONE;
codec->codec_type = AVMEDIA_TYPE_UNKNOWN;
goto fail;
}
codec->bit_rate = avio_rb32(pb);
codec->flags = avio_rb32(pb);
codec->flags2 = avio_rb32(pb);
codec->debug = avio_rb32(pb);
if (codec->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
return AVERROR(ENOMEM);
}
break;
case MKBETAG('S', 'T', 'V', 'I'):
if (f_stvi++) {
ret = AVERROR(EINVAL);
goto fail;
}
codec->time_base.num = avio_rb32(pb);
codec->time_base.den = avio_rb32(pb);
if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {
av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",
codec->time_base.num, codec->time_base.den);
ret = AVERROR_INVALIDDATA;
goto fail;
}
codec->width = avio_rb16(pb);
codec->height = avio_rb16(pb);
codec->gop_size = avio_rb16(pb);
codec->pix_fmt = avio_rb32(pb);
codec->qmin = avio_r8(pb);
codec->qmax = avio_r8(pb);
codec->max_qdiff = avio_r8(pb);
codec->qcompress = avio_rb16(pb) / 10000.0;
codec->qblur = avio_rb16(pb) / 10000.0;
codec->bit_rate_tolerance = avio_rb32(pb);
avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
codec->rc_eq = av_strdup(rc_eq_buf);
codec->rc_max_rate = avio_rb32(pb);
codec->rc_min_rate = avio_rb32(pb);
codec->rc_buffer_size = avio_rb32(pb);
codec->i_quant_factor = av_int2double(avio_rb64(pb));
codec->b_quant_factor = av_int2double(avio_rb64(pb));
codec->i_quant_offset = av_int2double(avio_rb64(pb));
codec->b_quant_offset = av_int2double(avio_rb64(pb));
codec->dct_algo = avio_rb32(pb);
codec->strict_std_compliance = avio_rb32(pb);
codec->max_b_frames = avio_rb32(pb);
codec->mpeg_quant = avio_rb32(pb);
codec->intra_dc_precision = avio_rb32(pb);
codec->me_method = avio_rb32(pb);
codec->mb_decision = avio_rb32(pb);
codec->nsse_weight = avio_rb32(pb);
codec->frame_skip_cmp = avio_rb32(pb);
codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));
codec->codec_tag = avio_rb32(pb);
codec->thread_count = avio_r8(pb);
codec->coder_type = avio_rb32(pb);
codec->me_cmp = avio_rb32(pb);
codec->me_subpel_quality = avio_rb32(pb);
codec->me_range = avio_rb32(pb);
codec->keyint_min = avio_rb32(pb);
codec->scenechange_threshold = avio_rb32(pb);
codec->b_frame_strategy = avio_rb32(pb);
codec->qcompress = av_int2double(avio_rb64(pb));
codec->qblur = av_int2double(avio_rb64(pb));
codec->max_qdiff = avio_rb32(pb);
codec->refs = avio_rb32(pb);
break;
case MKBETAG('S', 'T', 'A', 'U'):
if (f_stau++) {
ret = AVERROR(EINVAL);
goto fail;
}
codec->sample_rate = avio_rb32(pb);
codec->channels = avio_rl16(pb);
codec->frame_size = avio_rl16(pb);
break;
case MKBETAG('C', 'P', 'R', 'V'):
if (f_cprv++) {
ret = AVERROR(EINVAL);
goto fail;
}
enc = avcodec_find_encoder(codec->codec_id);
if (enc && enc->priv_data_size && enc->priv_class) {
buffer = av_malloc(size + 1);
if (!buffer) {
ret = AVERROR(ENOMEM);
goto fail;
}
avio_get_str(pb, size, buffer, size + 1);
if ((ret = ffm_append_recommended_configuration(st, &buffer)) < 0)
goto fail;
}
break;
case MKBETAG('S', '2', 'V', 'I'):
if (f_stvi++ || !size) {
ret = AVERROR(EINVAL);
goto fail;
}
buffer = av_malloc(size);
if (!buffer) {
ret = AVERROR(ENOMEM);
goto fail;
}
avio_get_str(pb, INT_MAX, buffer, size);
av_set_options_string(codec, buffer, "=", ",");
if ((ret = ffm_append_recommended_configuration(st, &buffer)) < 0)
goto fail;
break;
case MKBETAG('S', '2', 'A', 'U'):
if (f_stau++ || !size) {
ret = AVERROR(EINVAL);
goto fail;
}
buffer = av_malloc(size);
if (!buffer) {
ret = AVERROR(ENOMEM);
goto fail;
}
avio_get_str(pb, INT_MAX, buffer, size);
av_set_options_string(codec, buffer, "=", ",");
if ((ret = ffm_append_recommended_configuration(st, &buffer)) < 0)
goto fail;
break;
}
avio_seek(pb, next, SEEK_SET);
}
/* get until end of block reached */
while ((avio_tell(pb) % ffm->packet_size) != 0 && !pb->eof_reached)
avio_r8(pb);
/* init packet demux */
ffm->packet_ptr = ffm->packet;
ffm->packet_end = ffm->packet;
ffm->frame_offset = 0;
ffm->dts = 0;
ffm->read_state = READ_HEADER;
ffm->first_packet = 1;
return 0;
fail:
ffm_close(s);
return ret;
}
static int ffm_read_header(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
AVStream *st;
AVIOContext *pb = s->pb;
AVCodecContext *codec;
const AVCodecDescriptor *codec_desc;
int i, nb_streams;
uint32_t tag;
/* header */
tag = avio_rl32(pb);
if (tag == MKTAG('F', 'F', 'M', '2'))
return ffm2_read_header(s);
if (tag != MKTAG('F', 'F', 'M', '1'))
goto fail;
ffm->packet_size = avio_rb32(pb);
if (ffm->packet_size != FFM_PACKET_SIZE)
goto fail;
ffm->write_index = avio_rb64(pb);
/* get also filesize */
if (pb->seekable) {
ffm->file_size = avio_size(pb);
if (ffm->write_index && 0)
adjust_write_index(s);
} else {
ffm->file_size = (UINT64_C(1) << 63) - 1;
}
nb_streams = avio_rb32(pb);
avio_rb32(pb); /* total bitrate */
/* read each stream */
for(i=0;i<nb_streams;i++) {
char rc_eq_buf[128];
st = avformat_new_stream(s, NULL);
if (!st)
goto fail;
avpriv_set_pts_info(st, 64, 1, 1000000);
codec = st->codec;
/* generic info */
codec->codec_id = avio_rb32(pb);
codec_desc = avcodec_descriptor_get(codec->codec_id);
if (!codec_desc) {
av_log(s, AV_LOG_ERROR, "Invalid codec id: %d\n", codec->codec_id);
codec->codec_id = AV_CODEC_ID_NONE;
goto fail;
}
codec->codec_type = avio_r8(pb); /* codec_type */
if (codec->codec_type != codec_desc->type) {
av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",
codec_desc->type, codec->codec_type);
codec->codec_id = AV_CODEC_ID_NONE;
codec->codec_type = AVMEDIA_TYPE_UNKNOWN;
goto fail;
}
codec->bit_rate = avio_rb32(pb);
codec->flags = avio_rb32(pb);
codec->flags2 = avio_rb32(pb);
codec->debug = avio_rb32(pb);
/* specific info */
switch(codec->codec_type) {
case AVMEDIA_TYPE_VIDEO:
codec->time_base.num = avio_rb32(pb);
codec->time_base.den = avio_rb32(pb);
if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {
av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",
codec->time_base.num, codec->time_base.den);
goto fail;
}
codec->width = avio_rb16(pb);
codec->height = avio_rb16(pb);
codec->gop_size = avio_rb16(pb);
codec->pix_fmt = avio_rb32(pb);
codec->qmin = avio_r8(pb);
codec->qmax = avio_r8(pb);
codec->max_qdiff = avio_r8(pb);
codec->qcompress = avio_rb16(pb) / 10000.0;
codec->qblur = avio_rb16(pb) / 10000.0;
codec->bit_rate_tolerance = avio_rb32(pb);
avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
codec->rc_eq = av_strdup(rc_eq_buf);
codec->rc_max_rate = avio_rb32(pb);
codec->rc_min_rate = avio_rb32(pb);
codec->rc_buffer_size = avio_rb32(pb);
codec->i_quant_factor = av_int2double(avio_rb64(pb));
codec->b_quant_factor = av_int2double(avio_rb64(pb));
codec->i_quant_offset = av_int2double(avio_rb64(pb));
codec->b_quant_offset = av_int2double(avio_rb64(pb));
codec->dct_algo = avio_rb32(pb);
codec->strict_std_compliance = avio_rb32(pb);
codec->max_b_frames = avio_rb32(pb);
codec->mpeg_quant = avio_rb32(pb);
codec->intra_dc_precision = avio_rb32(pb);
codec->me_method = avio_rb32(pb);
codec->mb_decision = avio_rb32(pb);
codec->nsse_weight = avio_rb32(pb);
codec->frame_skip_cmp = avio_rb32(pb);
codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));
codec->codec_tag = avio_rb32(pb);
codec->thread_count = avio_r8(pb);
codec->coder_type = avio_rb32(pb);
codec->me_cmp = avio_rb32(pb);
codec->me_subpel_quality = avio_rb32(pb);
codec->me_range = avio_rb32(pb);
codec->keyint_min = avio_rb32(pb);
codec->scenechange_threshold = avio_rb32(pb);
codec->b_frame_strategy = avio_rb32(pb);
codec->qcompress = av_int2double(avio_rb64(pb));
codec->qblur = av_int2double(avio_rb64(pb));
codec->max_qdiff = avio_rb32(pb);
codec->refs = avio_rb32(pb);
break;
case AVMEDIA_TYPE_AUDIO:
codec->sample_rate = avio_rb32(pb);
codec->channels = avio_rl16(pb);
codec->frame_size = avio_rl16(pb);
break;
default:
goto fail;
}
if (codec->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
return AVERROR(ENOMEM);
}
}
/* get until end of block reached */
while ((avio_tell(pb) % ffm->packet_size) != 0 && !pb->eof_reached)
avio_r8(pb);
/* init packet demux */
ffm->packet_ptr = ffm->packet;
ffm->packet_end = ffm->packet;
ffm->frame_offset = 0;
ffm->dts = 0;
ffm->read_state = READ_HEADER;
ffm->first_packet = 1;
return 0;
fail:
ffm_close(s);
return -1;
}
/* return < 0 if eof */
static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int size;
FFMContext *ffm = s->priv_data;
int duration, ret;
switch(ffm->read_state) {
case READ_HEADER:
if ((ret = ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) < 0)
return ret;
ff_dlog(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
avio_tell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);
if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
FRAME_HEADER_SIZE)
return -1;
if (ffm->header[1] & FLAG_DTS)
if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)
return -1;
ffm->read_state = READ_DATA;
/* fall through */
case READ_DATA:
size = AV_RB24(ffm->header + 2);
if ((ret = ffm_is_avail_data(s, size)) < 0)
return ret;
duration = AV_RB24(ffm->header + 5);
if (av_new_packet(pkt, size) < 0) {
return AVERROR(ENOMEM);
}
pkt->stream_index = ffm->header[0];
if ((unsigned)pkt->stream_index >= s->nb_streams) {
av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);
av_packet_unref(pkt);
ffm->read_state = READ_HEADER;
return -1;
}
pkt->pos = avio_tell(s->pb);
if (ffm->header[1] & FLAG_KEY_FRAME)
pkt->flags |= AV_PKT_FLAG_KEY;
ffm->read_state = READ_HEADER;
if (ffm_read_data(s, pkt->data, size, 0) != size) {
/* bad case: desynchronized packet. we cancel all the packet loading */
av_packet_unref(pkt);
return -1;
}
pkt->pts = AV_RB64(ffm->header+8);
if (ffm->header[1] & FLAG_DTS)
pkt->dts = pkt->pts - AV_RB32(ffm->header+16);
else
pkt->dts = pkt->pts;
pkt->duration = duration;
break;
}
return 0;
}
/* seek to a given time in the file. The file read pointer is
positioned at or before pts. XXX: the following code is quite
approximative */
static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)
{
FFMContext *ffm = s->priv_data;
int64_t pos_min, pos_max, pos;
int64_t pts_min, pts_max, pts;
double pos1;
ff_dlog(s, "wanted_pts=%0.6f\n", wanted_pts / 1000000.0);
/* find the position using linear interpolation (better than
dichotomy in typical cases) */
if (ffm->write_index && ffm->write_index < ffm->file_size) {
if (get_dts(s, FFM_PACKET_SIZE) < wanted_pts) {
pos_min = FFM_PACKET_SIZE;
pos_max = ffm->write_index - FFM_PACKET_SIZE;
} else {
pos_min = ffm->write_index;
pos_max = ffm->file_size - FFM_PACKET_SIZE;
}
} else {
pos_min = FFM_PACKET_SIZE;
pos_max = ffm->file_size - FFM_PACKET_SIZE;
}
while (pos_min <= pos_max) {
pts_min = get_dts(s, pos_min);
pts_max = get_dts(s, pos_max);
if (pts_min > wanted_pts || pts_max <= wanted_pts) {
pos = pts_min > wanted_pts ? pos_min : pos_max;
goto found;
}
/* linear interpolation */
pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /
(double)(pts_max - pts_min);
pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;
if (pos <= pos_min)
pos = pos_min;
else if (pos >= pos_max)
pos = pos_max;
pts = get_dts(s, pos);
/* check if we are lucky */
if (pts == wanted_pts) {
goto found;
} else if (pts > wanted_pts) {
pos_max = pos - FFM_PACKET_SIZE;
} else {
pos_min = pos + FFM_PACKET_SIZE;
}
}
pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;
found:
if (ffm_seek1(s, pos) < 0)
return -1;
/* reset read state */
ffm->read_state = READ_HEADER;
ffm->packet_ptr = ffm->packet;
ffm->packet_end = ffm->packet;
ffm->first_packet = 1;
return 0;
}
static int ffm_probe(AVProbeData *p)
{
if (
p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&
(p->buf[3] == '1' || p->buf[3] == '2'))
return AVPROBE_SCORE_MAX + 1;
return 0;
}
static const AVOption options[] = {
{"server_attached", NULL, offsetof(FFMContext, server_attached), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
{"ffm_write_index", NULL, offsetof(FFMContext, write_index), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
{"ffm_file_size", NULL, offsetof(FFMContext, file_size), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
{ NULL },
};
static const AVClass ffm_class = {
.class_name = "ffm demuxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVInputFormat ff_ffm_demuxer = {
.name = "ffm",
.long_name = NULL_IF_CONFIG_SMALL("FFM (FFserver live feed)"),
.priv_data_size = sizeof(FFMContext),
.read_probe = ffm_probe,
.read_header = ffm_read_header,
.read_packet = ffm_read_packet,
.read_close = ffm_close,
.read_seek = ffm_seek,
.priv_class = &ffm_class,
};
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