[FFmpeg-devel] [RFC] WC3 decoder without AVPaletteControl
Reimar Döffinger
Reimar.Doeffinger
Sun Apr 12 13:26:33 CEST 2009
On Sun, Apr 12, 2009 at 12:19:07AM +0200, Reimar D?ffinger wrote:
> attached patch implements this.
> It is a bit ugly because it adds a lot of seeking to the demuxer, but I
> think for such a fringe format there is no point in extra work for avoiding it.
> The patch also adds two helper functions, one to increase the size of a
> packet and one that appends data read from a file to a possibly already
> filled packet.
> I expect that there will be more that a few bugs still, e.g. while the
> video looks visually ok in ffplay the FATE regressions do not match at
> all.
A minor update. It only fixes the gamma correction and provides a
fixed point integer-implementation, which might help explain some of
its weirdness like clipping to 253.
-------------- next part --------------
Index: libavcodec/xan.c
===================================================================
--- libavcodec/xan.c (revision 18467)
+++ libavcodec/xan.c (working copy)
@@ -35,7 +35,15 @@
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
+#include "bytestream.h"
+#define VGA__TAG MKTAG('V', 'G', 'A', ' ')
+#define PALT_TAG MKTAG('P', 'A', 'L', 'T')
+#define SHOT_TAG MKTAG('S', 'H', 'O', 'T')
+#define PALETTE_COUNT 256
+#define PALETTE_SIZE (PALETTE_COUNT * 3)
+#define PALETTES_MAX 256
+
typedef struct XanContext {
AVCodecContext *avctx;
@@ -51,6 +59,10 @@
unsigned char *buffer2;
int buffer2_size;
+ unsigned *palettes;
+ int palettes_count;
+ int cur_palette;
+
int frame_size;
} XanContext;
@@ -62,12 +74,6 @@
s->avctx = avctx;
s->frame_size = 0;
- if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
- (s->avctx->palctrl == NULL)) {
- av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
- return -1;
- }
-
avctx->pix_fmt = PIX_FMT_PAL8;
if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
@@ -403,6 +409,56 @@
static void xan_wc4_decode_frame(XanContext *s) {
}
+#ifdef FIXEDPOINT_GAMMA
+static inline unsigned mul(unsigned a, unsigned b)
+{
+ return (a * b) >> 16;
+}
+
+static inline unsigned pow4(unsigned a)
+{
+ unsigned square = mul(a, a);
+ return mul(square, square);
+}
+
+static inline unsigned pow5(unsigned a)
+{
+ return mul(pow4(a), a);
+}
+
+static uint8_t gamma_corr(uint8_t in) {
+ unsigned lo, hi = 0xff40, target;
+ int i = 15;
+ in = (in << 2) | (in >> 6);
+ lo = target = in << 8;
+ do {
+ unsigned mid = (lo + hi) >> 1;
+ unsigned pow = pow5(mid);
+ if (pow > target) hi = mid;
+ else lo = mid;
+ } while (--i);
+ return (pow4((lo + hi) >> 1) + 0x80) >> 8;
+}
+#else
+/**
+ * This is a gamma correction that xan3 applies to all palette entries.
+ *
+ * There is a peculiarity, namely that the values are clamped to 253 -
+ * it seems likely that this table was calculated by a buggy fixed-point
+ * implementation, the one above under FIXEDPOINT_GAMMA behaves like this for
+ * example.
+ * The exponent value of 0.8 can be explained by this as well, since 0.8 = 4/5
+ * and thus pow(x, 0.8) is still easy to calculate.
+ */
+static uint8_t gamma_corr(uint8_t in)
+{
+ in = (in << 2) | (in >> 6);
+ if (in >= 252)
+ return 253;
+ return round(pow(in / 256.0, 0.8) * 256);
+}
+#endif
+
static int xan_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
@@ -410,8 +466,50 @@
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
XanContext *s = avctx->priv_data;
- AVPaletteControl *palette_control = avctx->palctrl;
+ if (avctx->codec->id == CODEC_ID_XAN_WC3) {
+ const uint8_t *buf_end = buf + buf_size;
+ int tag = 0;
+ while (buf_end - buf > 8 && tag != VGA__TAG) {
+ unsigned *tmpptr;
+ int size;
+ int i;
+ tag = bytestream_get_le32(&buf);
+ size = bytestream_get_be32(&buf);
+ size = FFMIN(size, buf_end - buf);
+ switch (tag) {
+ case PALT_TAG:
+ if (size < PALETTE_SIZE)
+ return -1;
+ if (s->palettes_count >= PALETTES_MAX)
+ return -1;
+ tmpptr = av_realloc(s->palettes, (s->palettes_count + 1) * AVPALETTE_SIZE);
+ if (!tmpptr)
+ return AVERROR(ENOMEM);
+ s->palettes = tmpptr;
+ tmpptr += s->palettes_count * AVPALETTE_COUNT;
+ for (i = 0; i < PALETTE_COUNT; i++) {
+ int r = gamma_corr(*buf++);
+ int g = gamma_corr(*buf++);
+ int b = gamma_corr(*buf++);
+ *tmpptr++ = (r << 16) | (g << 8) | b;
+ }
+ s->palettes_count++;
+ break;
+ case SHOT_TAG:
+ if (size < 4)
+ return -1;
+ s->cur_palette = av_clip(bytestream_get_le32(&buf), 0, PALETTES_MAX - 1);
+ break;
+ case VGA__TAG:
+ break;
+ default:
+ buf += size;
+ break;
+ }
+ }
+ buf_size = buf_end - buf;
+ }
if (avctx->get_buffer(avctx, &s->current_frame)) {
av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
return -1;
@@ -421,10 +519,16 @@
if (!s->frame_size)
s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
+ if (avctx->codec->id == CODEC_ID_XAN_WC3) {
+ if (s->cur_palette < s->palettes_count)
+ memcpy(s->current_frame.data[1], s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE);
+ } else {
+ AVPaletteControl *palette_control = avctx->palctrl;
palette_control->palette_changed = 0;
memcpy(s->current_frame.data[1], palette_control->palette,
AVPALETTE_SIZE);
s->current_frame.palette_has_changed = 1;
+ }
s->buf = buf;
s->size = buf_size;
Index: libavcodec/avcodec.h
===================================================================
--- libavcodec/avcodec.h (revision 18467)
+++ libavcodec/avcodec.h (working copy)
@@ -2666,6 +2666,14 @@
void av_shrink_packet(AVPacket *pkt, int size);
/**
+ * Increase packet size, correctly zeroing padding
+ *
+ * @param pkt packet
+ * @param grow_by number of bytes by which to increase the size of the packet
+ */
+int av_grow_packet(AVPacket *pkt, int grow_by);
+
+/**
* @warning This is a hack - the packet memory allocation stuff is broken. The
* packet is allocated if it was not really allocated.
*/
Index: libavcodec/avpacket.c
===================================================================
--- libavcodec/avpacket.c (revision 18467)
+++ libavcodec/avpacket.c (working copy)
@@ -69,6 +69,24 @@
memset(pkt->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
}
+int av_grow_packet(AVPacket *pkt, int grow_by)
+{
+ void *new_ptr;
+ if (!grow_by)
+ return 0;
+ if (!pkt->size)
+ return av_new_packet(pkt, grow_by);
+ if (pkt->size + FF_INPUT_BUFFER_PADDING_SIZE > INT_MAX - grow_by)
+ return -1;
+ new_ptr = av_realloc(pkt->data, pkt->size + grow_by + FF_INPUT_BUFFER_PADDING_SIZE);
+ if (!new_ptr)
+ return AVERROR(ENOMEM);
+ pkt->data = new_ptr;
+ pkt->size += grow_by;
+ memset(pkt->data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+ return 0;
+}
+
int av_dup_packet(AVPacket *pkt)
{
if (((pkt->destruct == av_destruct_packet_nofree) || (pkt->destruct == NULL)) && pkt->data) {
Index: libavformat/avformat.h
===================================================================
--- libavformat/avformat.h (revision 18467)
+++ libavformat/avformat.h (working copy)
@@ -126,6 +126,17 @@
int av_get_packet(ByteIOContext *s, AVPacket *pkt, int size);
+/**
+ * Reads data and appends it to the current content of the AVPacket.
+ * If pkt->size is 0 it behaves like av_get_packet.
+ *
+ * @param pkt packet
+ * @param size amount of data to read
+ * @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
+ * will not be lost even if an error occurs.
+ */
+int av_append_packet(ByteIOContext *s, AVPacket *pkt, int size);
+
/*************************************************/
/* fractional numbers for exact pts handling */
Index: libavformat/utils.c
===================================================================
--- libavformat/utils.c (revision 18467)
+++ libavformat/utils.c (working copy)
@@ -277,6 +277,20 @@
return ret;
}
+int av_append_packet(ByteIOContext *s, AVPacket *pkt, int size)
+{
+ int ret;
+ int old_size;
+ if (!pkt->size)
+ return av_get_packet(s, pkt, size);
+ old_size = pkt->size;
+ ret = av_grow_packet(pkt, size);
+ if (ret < 0)
+ return ret;
+ ret = get_buffer(s, pkt->data + old_size, size);
+ av_shrink_packet(pkt, old_size + FFMAX(ret, 0));
+ return ret;
+}
int av_filename_number_test(const char *filename)
{
Index: libavformat/wc3movie.c
===================================================================
--- libavformat/wc3movie.c (revision 18467)
+++ libavformat/wc3movie.c (working copy)
@@ -57,69 +57,18 @@
#define WC3_FRAME_FPS 15
#define PALETTE_SIZE (256 * 3)
-#define PALETTE_COUNT 256
typedef struct Wc3DemuxContext {
int width;
int height;
- unsigned char *palettes;
- int palette_count;
int64_t pts;
int video_stream_index;
int audio_stream_index;
- AVPaletteControl palette_control;
+ AVPacket vpkt;
} Wc3DemuxContext;
-/**
- * palette lookup table that does gamma correction
- *
- * can be calculated by this formula:
- * for i between 0 and 251 inclusive:
- * wc3_pal_lookup[i] = round(pow(i / 256.0, 0.8) * 256);
- * values 252, 253, 254 and 255 are all 0xFD
- * calculating this at runtime should not cause any
- * rounding issues, the maximum difference between
- * the table values and the calculated doubles is
- * about 0.497527
- */
-static const unsigned char wc3_pal_lookup[] = {
- 0x00, 0x03, 0x05, 0x07, 0x09, 0x0B, 0x0D, 0x0E,
- 0x10, 0x12, 0x13, 0x15, 0x16, 0x18, 0x19, 0x1A,
- 0x1C, 0x1D, 0x1F, 0x20, 0x21, 0x23, 0x24, 0x25,
- 0x27, 0x28, 0x29, 0x2A, 0x2C, 0x2D, 0x2E, 0x2F,
- 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x38, 0x39,
- 0x3A, 0x3B, 0x3C, 0x3D, 0x3F, 0x40, 0x41, 0x42,
- 0x43, 0x44, 0x45, 0x46, 0x48, 0x49, 0x4A, 0x4B,
- 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53,
- 0x54, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C,
- 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64,
- 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C,
- 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74,
- 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
- 0x7D, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83,
- 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B,
- 0x8C, 0x8D, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
- 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x99,
- 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0xA0, 0xA1,
- 0xA2, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
- 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF,
- 0xB0, 0xB1, 0xB2, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6,
- 0xB7, 0xB8, 0xB9, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD,
- 0xBE, 0xBF, 0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4,
- 0xC5, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB,
- 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD0, 0xD1,
- 0xD2, 0xD3, 0xD4, 0xD5, 0xD5, 0xD6, 0xD7, 0xD8,
- 0xD9, 0xDA, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
- 0xDF, 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE4, 0xE5,
- 0xE6, 0xE7, 0xE8, 0xE9, 0xE9, 0xEA, 0xEB, 0xEC,
- 0xED, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF1, 0xF2,
- 0xF3, 0xF4, 0xF5, 0xF6, 0xF6, 0xF7, 0xF8, 0xF9,
- 0xFA, 0xFA, 0xFB, 0xFC, 0xFD, 0xFD, 0xFD, 0xFD
-};
-
-
static int wc3_probe(AVProbeData *p)
{
if (p->buf_size < 12)
@@ -142,18 +91,15 @@
AVStream *st;
char buffer[513];
int ret = 0;
- int current_palette = 0;
int bytes_to_read;
- int i;
- unsigned char rotate;
/* default context members */
wc3->width = WC3_DEFAULT_WIDTH;
wc3->height = WC3_DEFAULT_HEIGHT;
- wc3->palettes = NULL;
- wc3->palette_count = 0;
wc3->pts = 0;
wc3->video_stream_index = wc3->audio_stream_index = 0;
+ av_init_packet(&wc3->vpkt);
+ wc3->vpkt.data = NULL; wc3->vpkt.size = 0;
/* skip the first 3 32-bit numbers */
url_fseek(pb, 12, SEEK_CUR);
@@ -173,14 +119,8 @@
break;
case PC__TAG:
- /* need the number of palettes */
- url_fseek(pb, 8, SEEK_CUR);
- wc3->palette_count = get_le32(pb);
- if((unsigned)wc3->palette_count >= UINT_MAX / PALETTE_SIZE){
- wc3->palette_count= 0;
- return -1;
- }
- wc3->palettes = av_malloc(wc3->palette_count * PALETTE_SIZE);
+ /* number of palettes, unneeded */
+ url_fseek(pb, 12, SEEK_CUR);
break;
case BNAM_TAG:
@@ -203,23 +143,8 @@
case PALT_TAG:
/* one of several palettes */
- if ((unsigned)current_palette >= wc3->palette_count)
- return AVERROR_INVALIDDATA;
- if ((ret = get_buffer(pb,
- &wc3->palettes[current_palette * PALETTE_SIZE],
- PALETTE_SIZE)) != PALETTE_SIZE)
- return AVERROR(EIO);
-
- /* transform the current palette in place */
- for (i = current_palette * PALETTE_SIZE;
- i < (current_palette + 1) * PALETTE_SIZE; i++) {
- /* rotate each palette component left by 2 and use the result
- * as an index into the color component table */
- rotate = ((wc3->palettes[i] << 2) & 0xFF) |
- ((wc3->palettes[i] >> 6) & 0xFF);
- wc3->palettes[i] = wc3_pal_lookup[rotate];
- }
- current_palette++;
+ url_fseek(pb, -8, SEEK_CUR);
+ av_append_packet(pb, &wc3->vpkt, 8 + PALETTE_SIZE);
break;
default:
@@ -250,9 +175,6 @@
st->codec->width = wc3->width;
st->codec->height = wc3->height;
- /* palette considerations */
- st->codec->palctrl = &wc3->palette_control;
-
st = av_new_stream(s, 0);
if (!st)
return AVERROR(ENOMEM);
@@ -281,10 +203,6 @@
int packet_read = 0;
int ret = 0;
unsigned char text[1024];
- unsigned int palette_number;
- int i;
- unsigned char r, g, b;
- int base_palette_index;
while (!packet_read) {
@@ -302,22 +220,19 @@
case SHOT_TAG:
/* load up new palette */
- palette_number = get_le32(pb);
- if (palette_number >= wc3->palette_count)
- return AVERROR_INVALIDDATA;
- base_palette_index = palette_number * PALETTE_COUNT * 3;
- for (i = 0; i < PALETTE_COUNT; i++) {
- r = wc3->palettes[base_palette_index + i * 3 + 0];
- g = wc3->palettes[base_palette_index + i * 3 + 1];
- b = wc3->palettes[base_palette_index + i * 3 + 2];
- wc3->palette_control.palette[i] = (r << 16) | (g << 8) | (b);
- }
- wc3->palette_control.palette_changed = 1;
+ url_fseek(pb, -8, SEEK_CUR);
+ av_append_packet(pb, &wc3->vpkt, 8 + 4);
break;
case VGA__TAG:
/* send out video chunk */
- ret= av_get_packet(pb, pkt, size);
+ url_fseek(pb, -8, SEEK_CUR);
+ ret= av_append_packet(pb, &wc3->vpkt, 8 + size);
+ // ignore error if we have some data
+ if (wc3->vpkt.size > 0)
+ ret = 0;
+ *pkt = wc3->vpkt;
+ wc3->vpkt.data = NULL; wc3->vpkt.size = 0;
pkt->stream_index = wc3->video_stream_index;
pkt->pts = wc3->pts;
packet_read = 1;
@@ -371,7 +286,8 @@
{
Wc3DemuxContext *wc3 = s->priv_data;
- av_free(wc3->palettes);
+ if (wc3->vpkt.size > 0)
+ av_free_packet(&wc3->vpkt);
return 0;
}
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