diff options
Diffstat (limited to 'drivers/media/video/cx18/cx18-fileops.c')
| -rw-r--r-- | drivers/media/video/cx18/cx18-fileops.c | 54 |
1 files changed, 43 insertions, 11 deletions
diff --git a/drivers/media/video/cx18/cx18-fileops.c b/drivers/media/video/cx18/cx18-fileops.c index 23006f7d915..0b1dbc67e1a 100644 --- a/drivers/media/video/cx18/cx18-fileops.c +++ b/drivers/media/video/cx18/cx18-fileops.c @@ -176,6 +176,8 @@ static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block, *err = 0; while (1) { if (s->type == CX18_ENC_STREAM_TYPE_MPG) { + /* Process pending program info updates and pending + VBI data */ if (time_after(jiffies, cx->dualwatch_jiffies + msecs_to_jiffies(1000))) { cx->dualwatch_jiffies = jiffies; @@ -260,6 +262,20 @@ static size_t cx18_copy_buf_to_user(struct cx18_stream *s, len = ucount; if (cx->vbi.insert_mpeg && s->type == CX18_ENC_STREAM_TYPE_MPG && !cx18_raw_vbi(cx) && buf != &cx->vbi.sliced_mpeg_buf) { + /* + * Try to find a good splice point in the PS, just before + * an MPEG-2 Program Pack start code, and provide only + * up to that point to the user, so it's easy to insert VBI data + * the next time around. + */ + /* FIXME - This only works for an MPEG-2 PS, not a TS */ + /* + * An MPEG-2 Program Stream (PS) is a series of + * MPEG-2 Program Packs terminated by an + * MPEG Program End Code after the last Program Pack. + * A Program Pack may hold a PS System Header packet and any + * number of Program Elementary Stream (PES) Packets + */ const char *start = buf->buf + buf->readpos; const char *p = start + 1; const u8 *q; @@ -267,38 +283,54 @@ static size_t cx18_copy_buf_to_user(struct cx18_stream *s, int stuffing, i; while (start + len > p) { + /* Scan for a 0 to find a potential MPEG-2 start code */ q = memchr(p, 0, start + len - p); if (q == NULL) break; p = q + 1; + /* + * Keep looking if not a + * MPEG-2 Pack header start code: 0x00 0x00 0x01 0xba + * or MPEG-2 video PES start code: 0x00 0x00 0x01 0xe0 + */ if ((char *)q + 15 >= buf->buf + buf->bytesused || q[1] != 0 || q[2] != 1 || q[3] != ch) continue; + + /* If expecting the primary video PES */ if (!cx->search_pack_header) { + /* Continue if it couldn't be a PES packet */ if ((q[6] & 0xc0) != 0x80) continue; - if (((q[7] & 0xc0) == 0x80 && - (q[9] & 0xf0) == 0x20) || - ((q[7] & 0xc0) == 0xc0 && - (q[9] & 0xf0) == 0x30)) { - ch = 0xba; + /* Check if a PTS or PTS & DTS follow */ + if (((q[7] & 0xc0) == 0x80 && /* PTS only */ + (q[9] & 0xf0) == 0x20) || /* PTS only */ + ((q[7] & 0xc0) == 0xc0 && /* PTS & DTS */ + (q[9] & 0xf0) == 0x30)) { /* DTS follows */ + /* Assume we found the video PES hdr */ + ch = 0xba; /* next want a Program Pack*/ cx->search_pack_header = 1; - p = q + 9; + p = q + 9; /* Skip this video PES hdr */ } continue; } + + /* We may have found a Program Pack start code */ + + /* Get the count of stuffing bytes & verify them */ stuffing = q[13] & 7; /* all stuffing bytes must be 0xff */ for (i = 0; i < stuffing; i++) if (q[14 + i] != 0xff) break; - if (i == stuffing && - (q[4] & 0xc4) == 0x44 && - (q[12] & 3) == 3 && - q[14 + stuffing] == 0 && + if (i == stuffing && /* right number of stuffing bytes*/ + (q[4] & 0xc4) == 0x44 && /* marker check */ + (q[12] & 3) == 3 && /* marker check */ + q[14 + stuffing] == 0 && /* PES Pack or Sys Hdr */ q[15 + stuffing] == 0 && q[16 + stuffing] == 1) { - cx->search_pack_header = 0; + /* We declare we actually found a Program Pack*/ + cx->search_pack_header = 0; /* expect vid PES */ len = (char *)q - start; cx18_setup_sliced_vbi_buf(cx); break; |