[FFmpeg-devel] [PATCH v2 1/5] Interplay MVE: Implement MVE SEND_BUFFER operation

[Paul B Mahol]

On 6/20/17, Hein-Pieter van Braam <hp at tmm.cx> wrote:
> Interplay MVE movies have a SEND_BUFFER operation. Only after this
> command does the current decoding buffer get displayed. This is required
> for the other frame formats. They are fixed-size and can't always encode
> a full frame worth of pixeldata.
>
> This code prevents half-finished frames from being emitted.
>
> Signed-off-by: Hein-Pieter van Braam <hp at tmm.cx>
> ---
>  libavcodec/interplayvideo.c | 13 ++++++++-----
>  libavformat/ipmovie.c       | 16 +++++++++++-----
>  2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/libavcodec/interplayvideo.c b/libavcodec/interplayvideo.c
> index df3314d..9fed8f6 100644
> --- a/libavcodec/interplayvideo.c
> +++ b/libavcodec/interplayvideo.c
> @@ -990,6 +990,7 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
>      IpvideoContext *s = avctx->priv_data;
>      AVFrame *frame = data;
>      int ret;
> +    int send_buffer;
>
>      if (av_packet_get_side_data(avpkt, AV_PKT_DATA_PARAM_CHANGE, NULL)) {
>          av_frame_unref(s->last_frame);
> @@ -999,8 +1000,10 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
>      if (buf_size < 2)
>          return AVERROR_INVALIDDATA;

Checks only for 2 bytes.

>
> +    send_buffer = AV_RL8(avpkt->data);
> +
>      /* decoding map contains 4 bits of information per 8x8 block */
> -    s->decoding_map_size = AV_RL16(avpkt->data);
> +    s->decoding_map_size = AV_RL16(avpkt->data + 1);

Reads up to 3 bytes from input buffer. So above check needs to be updated.

>
>      /* compressed buffer needs to be large enough to at least hold an
> entire
>       * decoding map */
> @@ -1008,9 +1011,9 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
>          return buf_size;
>
>
> -    s->decoding_map = buf + 2;
> -    bytestream2_init(&s->stream_ptr, buf + 2 + s->decoding_map_size,
> -                     buf_size - s->decoding_map_size);
> +    s->decoding_map = buf + 3;
> +    bytestream2_init(&s->stream_ptr, buf + 3 + s->decoding_map_size,
> +                     buf_size - s->decoding_map_size - 3);
>
>      if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
>          return ret;
> @@ -1028,7 +1031,7 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
>
>      ipvideo_decode_opcodes(s, frame);
>
> -    *got_frame = 1;
> +    *got_frame = send_buffer;
>
>      /* shuffle frames */
>      av_frame_unref(s->second_last_frame);
> diff --git a/libavformat/ipmovie.c b/libavformat/ipmovie.c
> index 29eeaf6..0705d33 100644
> --- a/libavformat/ipmovie.c
> +++ b/libavformat/ipmovie.c
> @@ -91,6 +91,7 @@ typedef struct IPMVEContext {
>      uint32_t     palette[256];
>      int          has_palette;
>      int          changed;
> +    uint8_t      send_buffer;
>
>      unsigned int audio_bits;
>      unsigned int audio_channels;
> @@ -154,9 +155,9 @@ static int load_ipmovie_packet(IPMVEContext *s,
> AVIOContext *pb,
>
>      } else if (s->decode_map_chunk_offset) {
>
> -        /* send both the decode map and the video data together */
> +        /* send the decode map, the video data, and the send_buffer flag
> together */
>
> -        if (av_new_packet(pkt, 2 + s->decode_map_chunk_size +
> s->video_chunk_size))
> +        if (av_new_packet(pkt, 3 + s->decode_map_chunk_size +
> s->video_chunk_size))
>              return CHUNK_NOMEM;
>
>          if (s->has_palette) {
> @@ -178,8 +179,11 @@ static int load_ipmovie_packet(IPMVEContext *s,
> AVIOContext *pb,
>          avio_seek(pb, s->decode_map_chunk_offset, SEEK_SET);
>          s->decode_map_chunk_offset = 0;
>
> -        AV_WL16(pkt->data, s->decode_map_chunk_size);
> -        if (avio_read(pb, pkt->data + 2, s->decode_map_chunk_size) !=
> +        AV_WL8(pkt->data, s->send_buffer);
> +        s->send_buffer = 0;
> +
> +        AV_WL16(pkt->data + 1, s->decode_map_chunk_size);
> +        if (avio_read(pb, pkt->data + 3, s->decode_map_chunk_size) !=
>              s->decode_map_chunk_size) {
>              av_packet_unref(pkt);
>              return CHUNK_EOF;
> @@ -188,7 +192,7 @@ static int load_ipmovie_packet(IPMVEContext *s,
> AVIOContext *pb,
>          avio_seek(pb, s->video_chunk_offset, SEEK_SET);
>          s->video_chunk_offset = 0;
>
> -        if (avio_read(pb, pkt->data + 2 + s->decode_map_chunk_size,
> +        if (avio_read(pb, pkt->data + 3 + s->decode_map_chunk_size,
>              s->video_chunk_size) != s->video_chunk_size) {
>              av_packet_unref(pkt);
>              return CHUNK_EOF;
> @@ -444,6 +448,7 @@ static int process_ipmovie_chunk(IPMVEContext *s,
> AVIOContext *pb,
>          case OPCODE_SEND_BUFFER:
>              av_log(s->avf, AV_LOG_TRACE, "send buffer\n");
>              avio_skip(pb, opcode_size);
> +            s->send_buffer = 1;
>              break;
>
>          case OPCODE_AUDIO_FRAME:
> @@ -590,6 +595,7 @@ static int ipmovie_read_header(AVFormatContext *s)
>      ipmovie->video_pts = ipmovie->audio_frame_count = 0;
>      ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
>      ipmovie->decode_map_chunk_offset = 0;
> +    ipmovie->send_buffer = 0;
>
>      /* on the first read, this will position the stream at the first chunk
> */
>      ipmovie->next_chunk_offset = avio_tell(pb) + 4;
> --
> 2.9.4
>
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