Support the Hap chunked frame format

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

1 files changed, 159 insertions, 32 deletions

diff --git a/libavcodec/hapenc.c b/libavcodec/hapenc.c
index d828a096d5..4a31447c9e 100644
--- a/libavcodec/hapenc.c
+++ b/libavcodec/hapenc.c
@@ -1,6 +1,7 @@
 /*
  * Vidvox Hap encoder
  * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
+ * Copyright (C) 2015 Tom Butterworth <bangnoise@gmail.com>
  *
  * This file is part of Libav.
  *
@@ -42,8 +43,14 @@
 #include "internal.h"
 #include "texturedsp.h"
 
-/* A fixed header size allows to skip a memcpy */
-#define HEADER_SIZE 8
+#define HAP_MAX_CHUNKS 64
+
+enum HapHeaderLength {
+    /* Short header: four bytes with a 24 bit size value */
+    HAP_HDR_SHORT = 4,
+    /* Long header: eight bytes with a 32 bit size value */
+    HAP_HDR_LONG = 8,
+};
 
 static void compress_texture(AVCodecContext *avctx, const AVFrame *f)
 {
@@ -60,13 +67,133 @@ static void compress_texture(AVCodecContext *avctx, const AVFrame *f)
     }
 }
 
+/* section_length does not include the header */
+static void hap_write_section_header(PutByteContext *pbc,
+                                     enum HapHeaderLength header_length,
+                                     int section_length,
+                                     enum HapSectionType section_type)
+{
+    /* The first three bytes are the length of the section (not including the
+     * header) or zero if using an eight-byte header.
+     * For an eight-byte header, the length is in the last four bytes.
+     * The fourth byte stores the section type. */
+    bytestream2_put_le24(pbc, header_length == HAP_HDR_LONG ? 0 : section_length);
+    bytestream2_put_byte(pbc, section_type);
+
+    if (header_length == HAP_HDR_LONG) {
+        bytestream2_put_le32(pbc, section_length);
+    }
+}
+
+static int hap_compress_frame(AVCodecContext *avctx, uint8_t *dst)
+{
+    HapContext *ctx = avctx->priv_data;
+    int i, final_size = 0;
+
+    for (i = 0; i < ctx->chunk_count; i++) {
+        HapChunk *chunk = &ctx->chunks[i];
+        uint8_t *chunk_src, *chunk_dst;
+        int ret;
+
+        if (i == 0) {
+            chunk->compressed_offset = 0;
+        } else {
+            chunk->compressed_offset = ctx->chunks[i-1].compressed_offset
+                                       + ctx->chunks[i-1].compressed_size;
+        }
+        chunk->uncompressed_size = ctx->tex_size / ctx->chunk_count;
+        chunk->uncompressed_offset = i * chunk->uncompressed_size;
+        chunk->compressed_size = ctx->max_snappy;
+        chunk_src = ctx->tex_buf + chunk->uncompressed_offset;
+        chunk_dst = dst + chunk->compressed_offset;
+
+        /* Compress with snappy too, write directly on packet buffer. */
+        ret = snappy_compress(chunk_src, chunk->uncompressed_size,
+                              chunk_dst, &chunk->compressed_size);
+        if (ret != SNAPPY_OK) {
+            av_log(avctx, AV_LOG_ERROR, "Snappy compress error.\n");
+            return AVERROR_BUG;
+        }
+
+        /* If there is no gain from snappy, just use the raw texture. */
+        if (chunk->compressed_size >= chunk->uncompressed_size) {
+            av_log(avctx, AV_LOG_VERBOSE,
+                   "Snappy buffer bigger than uncompressed (%lu >= %lu bytes).\n",
+                   chunk->compressed_size, chunk->uncompressed_size);
+            memcpy(chunk_dst, chunk_src, chunk->uncompressed_size);
+            chunk->compressor = HAP_COMP_NONE;
+            chunk->compressed_size = chunk->uncompressed_size;
+        } else {
+            chunk->compressor = HAP_COMP_SNAPPY;
+        }
+
+        final_size += chunk->compressed_size;
+    }
+
+    return final_size;
+}
+
+static int hap_decode_instructions_length(HapContext *ctx)
+{
+    /*    Second-Stage Compressor Table (one byte per entry)
+     *  + Chunk Size Table (four bytes per entry)
+     *  + headers for both sections (short versions)
+     *  = chunk_count + (4 * chunk_count) + 4 + 4 */
+    return (5 * ctx->chunk_count) + 8;
+}
+
+static int hap_header_length(HapContext *ctx)
+{
+    /* Top section header (long version) */
+    int length = HAP_HDR_LONG;
+
+    if (ctx->chunk_count > 1) {
+        /* Decode Instructions header (short) + Decode Instructions Container */
+        length += HAP_HDR_SHORT + hap_decode_instructions_length(ctx);
+    }
+
+    return length;
+}
+
+static void hap_write_frame_header(HapContext *ctx, uint8_t *dst, int frame_length)
+{
+    PutByteContext pbc;
+    int i;
+
+    bytestream2_init_writer(&pbc, dst, frame_length);
+    if (ctx->chunk_count == 1) {
+        /* Write a simple header */
+        hap_write_section_header(&pbc, HAP_HDR_LONG, frame_length - 8,
+                                 ctx->chunks[0].compressor | ctx->opt_tex_fmt);
+    } else {
+        /* Write a complex header with Decode Instructions Container */
+        hap_write_section_header(&pbc, HAP_HDR_LONG, frame_length - 8,
+                                 HAP_COMP_COMPLEX | ctx->opt_tex_fmt);
+        hap_write_section_header(&pbc, HAP_HDR_SHORT, hap_decode_instructions_length(ctx),
+                                 HAP_ST_DECODE_INSTRUCTIONS);
+        hap_write_section_header(&pbc, HAP_HDR_SHORT, ctx->chunk_count,
+                                 HAP_ST_COMPRESSOR_TABLE);
+
+        for (i = 0; i < ctx->chunk_count; i++) {
+            bytestream2_put_byte(&pbc, ctx->chunks[i].compressor >> 4);
+        }
+
+        hap_write_section_header(&pbc, HAP_HDR_SHORT, ctx->chunk_count * 4,
+                                 HAP_ST_SIZE_TABLE);
+
+        for (i = 0; i < ctx->chunk_count; i++) {
+            bytestream2_put_le32(&pbc, ctx->chunks[i].compressed_size);
+        }
+    }
+}
+
 static int hap_encode(AVCodecContext *avctx, AVPacket *pkt,
                       const AVFrame *frame, int *got_packet)
 {
     HapContext *ctx = avctx->priv_data;
-    size_t final_size = ctx->max_snappy;
-    int ret, comp = HAP_COMP_SNAPPY;
-    int pktsize = FFMAX(ctx->tex_size, ctx->max_snappy) + HEADER_SIZE;
+    int header_length = hap_header_length(ctx);
+    int final_data_size, ret;
+    int pktsize = FFMAX(ctx->tex_size, ctx->max_snappy * ctx->chunk_count) + header_length;
 
     /* Allocate maximum size packet, shrink later. */
     ret = ff_alloc_packet(pkt, pktsize);
@@ -76,30 +203,15 @@ static int hap_encode(AVCodecContext *avctx, AVPacket *pkt,
     /* DXTC compression. */
     compress_texture(avctx, frame);
 
-    /* Compress with snappy too, write directly on packet buffer. */
-    ret = snappy_compress(ctx->tex_buf, ctx->tex_size,
-                          pkt->data + HEADER_SIZE, &final_size);
-    if (ret != SNAPPY_OK) {
-        av_log(avctx, AV_LOG_ERROR, "Snappy compress error.\n");
-        return AVERROR_BUG;
-    }
-
-    /* If there is no gain from snappy, just use the raw texture. */
-    if (final_size > ctx->tex_size) {
-        comp = HAP_COMP_NONE;
-        av_log(avctx, AV_LOG_VERBOSE,
-               "Snappy buffer bigger than uncompressed (%lu > %lu bytes).\n",
-               final_size, ctx->tex_size);
-        memcpy(pkt->data + HEADER_SIZE, ctx->tex_buf, ctx->tex_size);
-        final_size = ctx->tex_size;
-    }
+    /* Compress (using Snappy) the frame */
+    final_data_size = hap_compress_frame(avctx, pkt->data + header_length);
+    if (final_data_size < 0)
+        return final_data_size;
 
     /* Write header at the start. */
-    AV_WL24(pkt->data, 0);
-    AV_WL32(pkt->data + 4, final_size);
-    pkt->data[3] = comp | ctx->section_type;
+    hap_write_frame_header(ctx, pkt->data, final_data_size + header_length);
 
-    av_shrink_packet(pkt, final_size + HEADER_SIZE);
+    av_shrink_packet(pkt, final_data_size + header_length);
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
     return 0;
@@ -109,6 +221,7 @@ static av_cold int hap_init(AVCodecContext *avctx)
 {
     HapContext *ctx = avctx->priv_data;
     int ratio;
+    int corrected_chunk_count;
     int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
 
     if (ret < 0) {
@@ -125,7 +238,7 @@ static av_cold int hap_init(AVCodecContext *avctx)
 
     ff_texturedspenc_init(&ctx->dxtc);
 
-    switch (ctx->section_type & 0x0F) {
+    switch (ctx->opt_tex_fmt) {
     case HAP_FMT_RGBDXT1:
         ratio = 8;
         avctx->codec_tag = MKTAG('H', 'a', 'p', '1');
@@ -142,7 +255,7 @@ static av_cold int hap_init(AVCodecContext *avctx)
         ctx->tex_fun = ctx->dxtc.dxt5ys_block;
         break;
     default:
-        av_log(avctx, AV_LOG_ERROR, "Invalid format %02X\n", ctx->section_type);
+        av_log(avctx, AV_LOG_ERROR, "Invalid format %02X\n", ctx->opt_tex_fmt);
         return AVERROR_INVALIDDATA;
     }
 
@@ -150,7 +263,21 @@ static av_cold int hap_init(AVCodecContext *avctx)
      * beforehand the final size of the uncompressed buffer. */
     ctx->tex_size   = FFALIGN(avctx->width,  TEXTURE_BLOCK_W) *
                       FFALIGN(avctx->height, TEXTURE_BLOCK_H) * 4 / ratio;
-    ctx->max_snappy = snappy_max_compressed_length(ctx->tex_size);
+
+    /* Round the chunk count to divide evenly on DXT block edges */
+    corrected_chunk_count = av_clip(ctx->opt_chunk_count, 1, HAP_MAX_CHUNKS);
+    while ((ctx->tex_size / (64 / ratio)) % corrected_chunk_count != 0) {
+        corrected_chunk_count--;
+    }
+    if (corrected_chunk_count != ctx->opt_chunk_count) {
+        av_log(avctx, AV_LOG_INFO, "%d chunks requested but %d used.\n",
+                                    ctx->opt_chunk_count, corrected_chunk_count);
+    }
+    ret = ff_hap_set_chunk_count(ctx, corrected_chunk_count, 1);
+    if (ret != 0)
+        return ret;
+
+    ctx->max_snappy = snappy_max_compressed_length(ctx->tex_size / corrected_chunk_count);
 
     ctx->tex_buf  = av_malloc(ctx->tex_size);
     if (!ctx->tex_buf)
@@ -163,7 +290,7 @@ static av_cold int hap_close(AVCodecContext *avctx)
 {
     HapContext *ctx = avctx->priv_data;
 
-    av_freep(&ctx->tex_buf);
+    ff_hap_free_context(ctx);
 
     return 0;
 }
@@ -171,11 +298,11 @@ static av_cold int hap_close(AVCodecContext *avctx)
 #define OFFSET(x) offsetof(HapContext, x)
 #define FLAGS     AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
-    { "format", NULL, OFFSET(section_type), AV_OPT_TYPE_INT, { .i64 = HAP_FMT_RGBDXT1 }, HAP_FMT_RGBDXT1, HAP_FMT_YCOCGDXT5, FLAGS, "format" },
+    { "format", NULL, OFFSET(opt_tex_fmt), AV_OPT_TYPE_INT, { .i64 = HAP_FMT_RGBDXT1 }, HAP_FMT_RGBDXT1, HAP_FMT_YCOCGDXT5, FLAGS, "format" },
         { "hap",       "Hap 1 (DXT1 textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_RGBDXT1   }, 0, 0, FLAGS, "format" },
         { "hap_alpha", "Hap Alpha (DXT5 textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_RGBADXT5  }, 0, 0, FLAGS, "format" },
         { "hap_q",     "Hap Q (DXT5-YCoCg textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_YCOCGDXT5 }, 0, 0, FLAGS, "format" },
-
+    { "chunks", "chunk count", OFFSET(opt_chunk_count), AV_OPT_TYPE_INT, {.i64 = 1 }, 1, HAP_MAX_CHUNKS, FLAGS, },
     { NULL },
 };