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Add more resilience in reading ffm files. In particular, don't assume

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that the write pointer is correct. This can happen in certain failure
modes.

Originally committed as revision 2524 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Philip Gladstone 2003-11-19 02:34:40 +00:00
parent d445a7e9cc
commit 91628427ec
1 changed files with 66 additions and 0 deletions
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66
libavformat/ffm.c
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@ -51,6 +51,8 @@ typedef struct FFMContext {
uint8_t packet[FFM_PACKET_SIZE];
} FFMContext;
static int64_t get_pts(AVFormatContext *s, offset_t pos);
/* disable pts hack for testing */
int ffm_nopts = 0;
@ -64,6 +66,9 @@ static void flush_packet(AVFormatContext *s)
fill_size = ffm->packet_end - ffm->packet_ptr;
memset(ffm->packet_ptr, 0, fill_size);
if (url_ftell(pb) % ffm->packet_size)
av_abort();
/* put header */
put_be16(pb, PACKET_ID);
put_be16(pb, fill_size);
@ -202,6 +207,8 @@ static int ffm_write_header(AVFormatContext *s)
/* init packet mux */
ffm->packet_ptr = ffm->packet;
ffm->packet_end = ffm->packet + ffm->packet_size - FFM_HEADER_SIZE;
if (ffm->packet_end < ffm->packet)
av_abort();
ffm->frame_offset = 0;
ffm->pts = 0;
ffm->first_packet = 1;
@ -330,6 +337,8 @@ static int ffm_read_data(AVFormatContext *s,
frame_offset = get_be16(pb);
get_buffer(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
if (ffm->packet_end < ffm->packet)
av_abort();
/* if first packet or resynchronization packet, we must
handle it specifically */
if (ffm->first_packet || (frame_offset & 0x8000)) {
@ -363,6 +372,62 @@ static int ffm_read_data(AVFormatContext *s,
}
static void adjust_write_index(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
ByteIOContext *pb = &s->pb;
int64_t pts;
//offset_t orig_write_index = ffm->write_index;
offset_t pos_min, pos_max;
int64_t pts_start;
offset_t ptr = url_ftell(pb);
pos_min = 0;
pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
pts_start = get_pts(s, pos_min);
pts = get_pts(s, pos_max);
if (pts - 100000 > pts_start)
return;
ffm->write_index = FFM_PACKET_SIZE;
pts_start = get_pts(s, pos_min);
pts = get_pts(s, pos_max);
if (pts - 100000 <= pts_start) {
while (1) {
offset_t newpos;
int64_t newpts;
newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
if (newpos == pos_min)
break;
newpts = get_pts(s, newpos);
if (newpts - 100000 <= pts) {
pos_max = newpos;
pts = newpts;
} else {
pos_min = newpos;
}
}
ffm->write_index += pos_max;
}
//printf("Adjusted write index from %lld to %lld: pts=%0.6f\n", orig_write_index, ffm->write_index, pts / 1000000.);
//printf("pts range %0.6f - %0.6f\n", get_pts(s, 0) / 1000000. , get_pts(s, ffm->file_size - 2 * FFM_PACKET_SIZE) / 1000000. );
url_fseek(pb, ptr, SEEK_SET);
}
static int ffm_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
FFMContext *ffm = s->priv_data;
@ -384,6 +449,7 @@ static int ffm_read_header(AVFormatContext *s, AVFormatParameters *ap)
/* get also filesize */
if (!url_is_streamed(pb)) {
ffm->file_size = url_filesize(url_fileno(pb));
adjust_write_index(s);
} else {
ffm->file_size = (uint64_t_C(1) << 63) - 1;
}